Interactive NY redistricting map with cartoDB and more

UPDATE Nov. 5, 2012

In preparation for the Nov. 2012 election, many news organizations and others are linking to our interactive State Legislature and Congressional redistricting maps. We’ve posted examples at the Center for Urban Research website.


UPDATE Sept. 7, 2012

We’ve updated our map of redistricted State Senate and Assembly districts, highlighting the differences in race/ethnicity characteristics between total population and voter-eligible population – in other words, comparing the characteristics of all those who live in the new districts versus the smaller group who will be eligible to vote for each district’s representatives.  In some cases the differences are striking.

Our examination of the district-by-district data is available here.


New York State, like all other states, is in the midst of redrawing its legislative district lines. To help you follow along, our team at the Center for Urban Research has launched an interactive redistricting map for New York.  We collaborated with The New York World to develop the maps (though we encourage anyone and everyone to use them!).

The World’s reporters and editors are using our maps to go between the lines and explain how redistricting really works in the Empire State. (Here’s their first piece: The art of redistricting war.)  And we hope you’ll be able to use the maps too, to help answer questions such as:

  • Will you still be represented by the same State Senate or Assembly district you live in now?
  • Will you live in the newly proposed (and controversial) 63rd Senate district?
  • Is your neighborhood, town, or county going to be “carved up” by a new legislative seat?
  • Will your community’s historical voting power be diluted by the new districts?

We have some examples of gerrymandering at our Center’s website. In the meantime, here’s how you can use the maps.

Map features

The maps compare the current and proposed district lines (which our team mapped based on Census block lists published by the state’s redistricting task force, known as LATFOR). Here’s how they work:

  • Enter your address to find out what district currently represents you, and which proposed district you’d live in.
  • The current districts are on the left, and the proposed districts on the right.
  • You can also click on either map to highlight the current and proposed districts. As you move one map, the other moves in sync.
  • When you enter an address or click on the map, an info window pops up listing the current and proposed districts. You can click the link for the current district to go to that Senator or Assemblymember’s website.
  • Switch between State Senate and Assembly districts. Congressional districts will be posted once the data is available from LATFOR.
  • You can zoom in to street level, or zoom out to a statewide view. Switch between a street basemap or an aerial view from Microsoft’s Bing maps to see geographic details.

If you’re using the “Overlay” view, you can move the transparency slider to the right to display proposed districts, and to the left to fade back to current districts. The video below shows how:

If you want to share the map you’ve made, click the “Link” in the upper right of the map page to get a direct link to the area of the map you’re viewing. It will look like this:

http://www.urbanresearchmaps.org/nyredistricting/map.html?
lat=40.72852&lon=-73.99655&zoom=13&maptype=SIDEBYSIDE
&districttype=SENATE
  • You can share this on Twitter, Facebook, etc and email it to friends and colleagues.
  • You can also embed the map at your site. Use this link …
http://www.urbanresearchmaps.org/nyredistricting/map.html?output=embed
  • … or add < &output=embed > to any of the direct links you create, like this:
http://www.urbanresearchmaps.org/nyredistricting/map.html?
lat=40.72852&lon=-73.99655&zoom=13&maptype=SIDEBYSIDE
&districttype=SENATE&output=embed
  • … or wrap the snippet below in an iframe tag (I’d wrap it myself, but wordpress.com strips out iframe tags):
src="http://www.urbanresearchmaps.org/nyredistricting/map.html?output=embed" 
frameborder="0" marginwidth="0" marginheight="0" 
scrolling="no" width="600" height="700"

Side-by-side maps with OpenLayers

We borrowed from our “Census Comparinator” mapping site that Dave Burgoon artfully developed, in order to provide three ways to compare the current and proposed legislative districts:

  • a side-by-side view — two maps that are synced and move as one;
  • an overlay — a single map where you can fade between current and proposed districts; and
  • the vertical “before-and-after” slider approach.

I blogged about the Comparinator approach here and here. John Reiser also gave the technique a shoutout at his “Learning Web Mapping” blog for Rowan University.

With Census data, our “Comparinator” approach helped visualize changing spatial patterns of race/ethnicity trends – in cartographic terms, between two choropleth maps. With legislative districts, the comparison is between two sets of boundary files with no inner fill. So here we’ve set the side-by-side view as the default — we think the side by side maps give the easiest way of visualizing how the districts may change. But we also give you the option of viewing the districts with our vertical slider bar if you’d like, or the overlay.

Behind the scenes

For the proposed districts, we used ArcGIS to create the legislative district shapefiles based on LATFOR’s Census block assignment lists.  The current district boundaries are from the Census Bureau’s TIGER files (here’s the FTP page if you’d like to download the “lower” house districts — in New York, that’s the Assembly — or the “upper” house shapefiles — the State Senate).

We use OpenLayers for the map display and navigation with this application, as we’ve done with most of our other interactive maps. OpenLayers is easy to use, enables us to access Bing map tiles directly (so the basemap performance is smooth), and provides a robust JavaScript library for online maps.

That said, newer approaches such as Leaflet.js enable more interaction such as mouseovers, so we’ve started experimenting with some impressive new tools. More to follow!

One of those new tools is the powerful backend geospatial database engine from the team at Vizzuality: cartoDB. Hosting the legislative district shapefiles on cartoDB provided lots of advantages over hosting the data ourselves or setting up an Amazon cloud instance on our own. cartoDB provides:

  • great performance — not only for the district boundaries, but soon we’ll be adding election district maps to show voting patterns within each Senate and Assembly district. We don’t want to bother with creating pre-rendered tiles for this data. cartoDB will render it speedily on the fly.
  • cartographic flexibility: cartoDB uses cartoCSS for map symbology and labeling. Though there are still some quirks with cartoCSS, it was easy to grasp and it’s basically just CSS, so it makes styling easy if you’re familiar with modern web design. And cartoCSS incorporates scale-dependent rendering as well as attribute-based symbology, which makes it powerful and flexible. CartoCSS can be implemented using the cartoDB management interface, or programmatically.
  • easy data management: if you know SQL — and even better, if you’re familiar with SQL commands with PostGIS — you can quickly and easily modify tables, filter data, and perform spatial operations. (The screenshots at the cartoDB github page offer some examples.) Very cool.
  • scaling: cartoDB uses PostGIS and makes use of Amazon’s platform. So if our maps go viral, we’re ready for the usage spike!
  • open source: if you want to manage your own instance of cartoDB, just download the code and go! Big props to Vizzuality for an amazing geospatial toolkit.

Other thanks go to:

  • LATFOR, the state’s redistricting task force. Whatever you think about their redistricting process, they’ve done a great job with open data. They’ve not only posted the list of Census blocks that make up each proposed legislative district. But they also posted a wealth of data at the Census block level and also at the election district level (with a crosswalk between EDs and Census “voter tabulation districts”). This data is indispensable for visualizing, analyzing, and (hopefully) making sense of the new districts.
  • Dave Burgoon and the CUR team. Dave put together the redistricting mapping site in record time. Although it’s based on work he had already done with the Census Comparinator maps, it still involved substantial modifications and enhancements. But he made it happen as professionally and elegantly as always.
  • The New York World. We had been planning to create an interactive mapping application to build on our Census Comparinator site and to help people visualize the impacts of the redistricting process and demographic changes more broadly.  But the World team – Alyssa Katz, Michael Keller, and Sasha Chavkin – met with us a few weeks ago to discuss how we could collaborate on analyzing and mapping the upcoming district proposals from LATFOR.  The discussion inspired us to roll out a mapping site specific to New York State and focused on comparing the current and proposed districts. We’re thrilled to be able to work closely with them on this project (watch for more maps and data in the near future!).
  • The Hagedorn Foundation. The Foundation has provided funding support for our efforts to map and analyze Census data for a variety of civic engagement purposes, especially for Hagedorn’s Long Island-based grantees but also nationwide. Their support has been essential for us to develop innovative mapping applications like the NYS redistricting maps – not to advocate specific district plans one way or another, but to give local residents and others the tools they need to understand the impact of redistricting and hopefully get involved in the process.

Proposed NYS Senate & Assembly districts available in GIS format

UPDATE Nov. 5, 2012

In preparation for the Nov. 2012 election, many news organizations and others are linking to our interactive State Legislature and Congressional redistricting maps. We’ve posted examples at the Center for Urban Research website.


UPDATE Sept. 7, 2012

We’ve updated our map of redistricted State Senate and Assembly districts, highlighting the differences in race/ethnicity characteristics between total population and voter-eligible population – in other words, comparing the characteristics of all those who live in the new districts versus the smaller group who will be eligible to vote for each district’s representatives.  In some cases the differences are striking.

Our examination of the district-by-district data is available here.  The New York Times gave our analysis a shout-out in their CityRoom primary election day column.

You can also visit our original NYS redistricting “comparinator” map described below, at www.urbanresearchmaps.org/nyredistricting/map.html


UPDATE February 5, 2012

You can visualize these proposed districts in relation to the current New York State Senate and Assembly districts with our new interactive redistricting map.  We developed the interactive map in collaboration with The New York World, and here’s an article using the maps to describe the redistricting process in the Empire State.  For more background on the interactive map, visit this blog post.


Original Post

If you’re hoping to use GIS or any of the online mapping tools to map the legislative district lines in New York State that were proposed today by the state’s redistricting task force, you’ll have some work to do.  The Task Force released PDF maps as well as “block assignment lists” for the proposed districts.

Unless you’d like to use the shapefiles and/or KML files that our team at the CUNY Graduate Center created!  Here’s our web page with the info: http://www.urbanresearch.org/news/proposed-nys-districts-in-gis-format

Happy redistricting mapping!

NYC neighborhood changes mapped with aerial imagery, historic land use data

Our team at the CUNY Graduate Center has enhanced the OASISnyc.net mapping site with new data and features to visualize neighborhood change across the city. On the eve of the 10th anniversary of 9/11, the updates help provide context for the transformation taking place in lower Manhattan, as well as in other key areas of the city.

I’ve only included some of the highlights below. Our OASIS wiki has more details plus screenshots and other examples.

2010 Aerial Imagery

We’ve added new aerial imagery, thanks to the NYS GIS Clearinghouse. Now you can view overhead images from 2010 (as well as 1996, 2004, 2006, and 2008) throughout New York City and Long Island. (The 1996 imagery is from NYC DoITT, 2004 is from USGS, and the other years are from the NYS GIS Clearinghouse).

For example, you can see what the World Trade Center site looked like from above in 1996, and then in 2006, and more recently in 2010. The overhead images show clearly how the building footprints are reflected in the memorial plaza fountains now under construction.

WTC 1996

OASIS_WTC_1996.png

WTC 2006

OASIS_WTC_2006.png

WTC 2010

OASIS_WTC_2010.png

Visualize Aerial Photo Changes like a Timelapse Movie

We’ve also changed the way you can view the imagery over time. Now you can move the aerial timeline slider across years to transition from one year to the next, creating the effect of a timelapse movie within the OASIS map.

aerialtimelineslider200.png

You can move the slider as slow or as fast as you’d like.

A good example of the new timelapse feature is Shea Stadium (now Citi Field) in Queens. The images below illustrate the transition in recent years.

Shea Stadium (2006)

Shea_2006.png

Shea Stadium (2006-08)

Shea_06-08.png

Citi Field almost done (2008-10)

Shea_08-10.png

Citi Field (2010)

Shea_2010.png

Land Use Changes Citywide

Since 2010, OASIS has provided the ability to display historical land use patterns (for 2003 through 2009). This gives you the ability to easily see how patterns have changed in key areas of the city.

In lower Manhattan, the area around the World Trade Center site has changed substantially in the past 10 years. Of course reconstruction is underway at the WTC site itself, but the surrounding community has become much more residential. The land use maps below from OASIS visualize some of these changes (yellow and orange are residential properties, brown is vacant, and light red is commercial).

North Battery Park City & TriBeCa vacant land (and WTC empty): 2003

LMLU_WTCBPC03sm.png

Residential towers built, WTC site in redevelopment

LMLU_WTCBPC10sm.png

The maps below highlight the changes from commercial office buildings to residential towers, such as the block between Broad and Hanover streets & Wall and Exchange streets — especially the JP Morgan Building at 15 Broad St and the National City Bank Building at 55 Wall St.

Financial District commercial property circa 2003

LMComm03.png

Replaced by residential by 2010

LMResidential10.png

More Community Data

The latest example of linking mapped information from grassroots groups is the layer of skate parks in the city by longtime OASIS partner Open Road of NY. (The OASIS community mapping effort is based on Google’s new Fusion Tables service; more info here.)

Here’s the link to the map on OASIS, and the original Google map from Open Road.

We’ve also added the locations of stalled development sites across the city (based on a map from Crain’s New York Business), and the city’s hurricane evacuation centers (more on that here).

Coastal storm impact risk mapped on Long Island

UPDATED (Sunday, Oct. 28, 2012 11am)

In anticipation of Hurricane Sandy, you can use the Long Island Index mapping site to view the areas that would be at greatest risk from the storm.

You can also use Nassau County‘s or Suffolk County‘s websites for more information.


ORIGINAL POST (August 2011)

The latest tracking information for Hurricane Irene (as of Friday morning, 8/26) shows that the storm is likely going to pass east of New York City and make a head on collision with Long Island.  Newsday is reporting that it will hit western Suffolk County’s south shore on Saturday with “tropical-storm-force winds” and then ramp up to 110 mph winds by Sunday.  Yikes!

To help prepare for the storm, our team at the CUNY Graduate Center in collaboration with the Long Island Index has updated the Index’s mapping website with areas at greatest risk of hurricane-level storms.

Here’s the map:

This news release [PDF] provides more information.  The yellow-to-red shaded areas are “coastal storm impact zones.”  In 2005, the New York State Office of Emergency Management developed a map of areas that would be at greatest risk of hurricane impacts based on wind speed and other factors.

The shorthand for the map is a “SLOSH” map, because the zones of impact are based on NOAA’s “Sea, Lake and Overland Surge from Hurricanes” (SLOSH) model projections of vertical surge heights associated with category 1 – 4 storms.  In order to map this information at the Index site, we downloaded the SLOSH data from the NYS GIS Clearinghouse website (metadata here) and used the following color shading to represent the zones:

  • A Category 1 storm (impact areas shown on the map in yellow) means winds of 74-95 mph.
  • A Category 2 storm (impact areas shown on the map in light orange) means winds of 96-110 mph.
  • A Category 3 storm (impact areas shown on the map in dark orange) means winds of 111-130 mph.
  • A Category 4 storm (impact areas shown on the map in red) means winds of 131 mph or more.
If you’re in an area highlighted on the map, be sure to contact your local officials and follow media reports about the hurricane’s progress. Nassau County’s Office of Emergency Management has posted a map of evacuation routes if it comes to that:
Hopefully Irene passes us by, but if not: be prepared.  Better safe than sorry.

Coastal storm impact risk mapped in NYC

UPDATED (Monday, Oct. 29, 2012 1pm)

If you need to locate any of NYC’s 76 hurricane evacuation shelters, you can use the OASIS mapping site.

You can also use NYC.gov to find out the latest with Hurricane Sandy.


UPDATED (8/25/11 9am): We’ve added a temporary map layer on OASIS showing the locations of NYC’s hurricane evacuation centers. Here’s the link: http://bit.ly/oBsUY8 . It’s easy to use:

  • Hover your mouse over each one to highlight it (the site details will also be highlighted in the panel on the right).
  • Click on a map marker to bring the site details up to the top of the list.
  • Double-click on a site in the list and the map will zoom in right to that location.

You can type in your address above the map to see if you’re in an area that’s at risk of storm impacts, and how close you are to an evacuation center. The OASIS map automatically also shows any nearby subway stations. And you can add any other layers from the Legend list to the right of the map.

For more information about Hurricane Irene and what you should do to prepare, visit NYC’s website.

UPDATED (8/24/11 12 noon): We’ve expanded the map layer showing hurricane impact zones throughout the downstate region. It now shows potential impact zones on Long Island’s south shore, as well as some areas along the coast of the Long Island Sound.

ORIGINAL POST

For the past several years the www.OASISnyc.net mapping site has displayed a map of “coastal storm impact zones” in New York City (in addition to the wealth of other mapped data included with OASIS). This coming weekend, it seems like the coastal storm map may be especially useful with city officials bracing for the risk of Hurricane Irene bringing 72 mph winds or more to the NYC region by Sunday.

In 2005, the New York State Office of Emergency Management developed a map of areas that would be at greatest risk of hurricane impacts based on wind speed and other factors. The shorthand for the map is a “SLOSH” map, because the zones of impact are based on NOAA’s “Sea, Lake and Overland Surge from Hurricanes” (SLOSH) model projections of vertical surge heights associated with category 1 – 4 storms.

In 2006, we downloaded the SLOSH data from the NYS GIS Clearinghouse website (metadata here), and used the following color shading to represent the zones:

  • A Category 1 storm (impact areas shown on the map in yellow) means winds of 74-95 mph.
  • A Category 2 storm (impact areas shown on the map in light orange) means winds of 96-110 mph.
  • A Category 3 storm (impact areas shown on the map in dark orange) means winds of 111-130 mph.
  • A Category 4 storm (impact areas shown on the map in red) means winds of 131 mph or more.

Here’s the map:

Through the OASIS website, you can easily enter your address and find out if you’re in an area that might be at greatest risk of the hurricane, depending on how severe the winds are by the time Irene moves up the coast. But the real power of OASIS’s maps is that you can do much more. For example, you can:

  • customize the OASIS map to show transit routes, schools, public housing, and libraries in or near the zones;
  • use OASIS’s mapping tools to see areas near the zones that have been recently developed (using the 1996-2010 aerial image timeline tool);
  • zoom in to see individual property boundaries and click on each one to determine ownership, zoning, and land use characteristics; and
  • find out which elected officials represent the area, as well as the local Community Board (good sources for planning and safety resources).

In the images below, I’ve used the aerial timeline slider and the dynamic transparency tool to show recent housing development in an area at risk of impact from a Category 1 storm, along South Beach on Staten Island (at the OASIS website, you can click and drag the name of any map layer in the Legend to the “Transparency Control” box at the bottom of the legend and make it more or less transparent, so the layers underneath can shine through):

Sparse housing near the beach (1996)

Dense housing development (2010)

The zones mapped on OASIS closely mirror the city’s hurricane evacuation zones (mapped here [PDF] and described here). The city also provides a Hurricane Evacuation Zone Finder where you can enter an address and get useful safety tips depending on your zone.

The message: hopefully Irene passes us by, but if not: be prepared. Better safe than sorry.

Innovative map comparisons – Census change in 15 cities

Our team at the Center for Urban Research (at the CUNY Graduate Center) has updated our interactive maps showing race/ethnicity patterns from 2000 and 2010 in major cities across the US. We’ve enhanced the maps in several ways:

  1. Added more cities. We now have 15 major urban regions mapped across the US (Atlanta, Baltimore, Boston, Charlotte, Chicago, Detroit, Houston, Los Angeles, Miami, New York, Orlando, Philadelphia, Phoenix, San Francisco, and Washington D.C.).
  2. The maps now have three ways of comparing 2000 and 2010 racial patterns:
  3. We color-coded the population change data in the popup window. Population increase is shown in green; decrease is shown in red. See image below.

Here’s our news release with more info.

Btw, we’ve also updated our static maps to show New York City Council districts, to begin to get a sense of how demographic changes will shape upcoming redistricting efforts at the local level.  Here’s the link:www.urbanresearchmaps.org/plurality/nyccouncil.htm (For the static maps, you can view 2000-2010 demographic change with the vertical slider bar, but you can’t zoom in/out, etc.)

An initial version of the maps launched in June with the vertical bar technique, integrating it with interactive, online maps for the first time. Our Center crafted the maps so you could not only drag the bar left and right but also zoom in and out, click on the map to obtain detailed block-level population counts, and change the underlying basemap from a street view to an aerial image (via OpenLayers use of Microsoft’s Bing maps tiles), while also changing the transparency of the thematic Census patterns.

The latest iteration of CUNY’s Census maps continues to use the vertical slider but now incorporates this technique with two more comparison options. Each approach serves different purposes:

  1. The vertical slider bar provides a “before (2000) and after (2010)” visualization of change, either regionally or at the scale of a city neighborhood.
  2. The side-by-side comparison is ideal for lingering over a given area, especially at the local level, taking the time to absorb the differences in demographic patterns mapped with 2000 Census data on the left and 2010 on the right. We incorporated this approach specifically at the suggestion of the great interactive team at the Chicago Tribune, who have created some similar Census maps.
  3. The single-map 2010/2000 overlay is especially helpful for revealing the increase in diversity over a given area.

For example, you can zoom to Atlanta, GA on the single-map overlay and see the city’s predominantly Black population in 2000 surrounded by suburban Census blocks shaded dark blue, denoting a White population of 90% or more (see images below). As you transition the map from 2000 to 2010, the dark blue in the suburbs fades to a lighter shade (indicating a more mixed population demographically) coupled with more Census blocks shaded green, purple, and orange – each corresponding to communities that are now predominantly (even if only by a few percentage points) Hispanic, Asian, or Black respectively. This pattern is replicated in many of the urban regions featured at the website.

Atlanta & suburbs in 2000

Race/ethnicity change in Atlanta by 2010

Eventually we’ll be moving all this from pre-rendered tiles to vector tiles. CUR’s application architect Dave Burgoon contributed code he developed to TileStache to enable TileStache to produce AMF-based output for use in Flash-based interactive mapping applications. This will give us flexibility in mapping as many Census variables as needed, and also providing complete geographic coverage (hopefully down to the block level) nationwide. That’s the plan, anyway! Stay tuned.

Credits

Funding for much of the Center’s recent work on Census issues has been provided by the Building Resilient Regions Project of the John D. and Catherine T. MacArthur Foundation, the Hagedorn Foundation, as well as support from the CUNY Graduate Center and the City University of New York.

Several people provided feedback and helpful editorial suggestions on earlier versions of the maps and narrative. Though the materials at this site were prepared by the Center for Urban Research, those invdividuals improved our work. We greatly appreciate their contributions.

Mapping the Cityscape exhibit

This summer the Center for Architecture in New York is all about maps.  One of the main exhibits at the Center, “Mapping the Cityscape”, features a dozen or so wall-mounted 8-foot-high maps of Manhattan — different representations and views from 1609 to the present.  Several panel discussions are accompanying the exhibit, including two this week (“Mapping Manhattan” and “Mapping Risk“).  Originally scheduled for the month of July, by popular demand the exhibit will be open through the end of August (Aug. 27th).

The exhibit came out of a panel discussion in May at the Center, organized by Abby Suckle of CultureNOW, with a broad group of participants: Matt Knutzen of the NY Public Library Map Division, John Tauranac of subway mapping fame, Laura Kurgan of Columbia University, and me discussing the OASISnyc mapping site — along with respondents from Google and the Wall Street Journal.  The panel covered lots of ground, from the Library’s invaluable collection of historical maps (now being digitized and geo-referenced) to the evolution of transit mapping in New York to the OASISnyc online mapping site (parks, open space, and much much more) to Columbia’s “Million Dollar Blocks” project to CultureNOW’s mobile maps to the latest from Google and others.  The hall was packed, the audience had lots of questions, and apparently they wanted more — hence the decision by the Center to transform the panel discussion into a summer-long exhibit.

Here are some photos of what you’ll see when you visit:

OASIS maps – each “slice” of the two maps above highlights the different types of mapped data you can display and analyze at the OASIS website.

Million Dollar Blocks – Columbia University’s Spatial Design Lab project that mapped the impact of prison policies on local neighborhoods in New York.

Mannahatta – the Wildlife Conservation Society’s take on what Manhattan likely looked like in 1609; an amazing project, rich with insights, analysis, and visual power.

NY Public Library – historical maps brought to life.

Maps of ecological patterns, historical maps overlain with current geography, transit mapping …

… and land use patterns, cultural icons, and more.

The exhibit opening in early July was packed — Center director Rick Bell & exhibit curator Abby Suckle talk to the crowd about the event:

If you’re interested in how maps — and the very definition of mapping and understanding/visualizing spatial relationships — are changing through the latest interactive technologies,  then this exhibit is for you.  Or if you’re interested in the history of visualizing New York City through maps, then this exhibit is for you.  Either way, please stop by, check out the maps, and attend one of the public programs.  It’ll be a cartographically illuminating experience.

(Exhibit logo from Center for Architecture website.  All photos: Steven Romalewski)

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