Impact of Census 2010 Population Data on NYS Legislative Districts and Congress

The Census Bureau has released the official 2010 decennial census counts for New York, documenting an increase in the state's population of 2.1%, from 18.9 million in 2000 to 19,378,102. This number is slightly less than the estimated 2005-09 population announced by the Bureau this past December (19,421,055 people). But this week's numbers are the official tallies that will drive the upcoming redistricting process, as well as many other policy decisions.

Our maps below compare the 2010 populations of the state's current Congressional and state Senate and Assembly districts with the average district size, identify areas of the state where Congressional districts may be eliminated (New York State will lose two seats, from 29 to 27), and show how the state's legislative districts may need to shift.

Congressional districts - downstate (LI/NYC) as likely to lose a seat as western NY

The map below shows how much New York's current districts differ in population size from the ideal apportionment population, and therefore how the state's existing 29 congressional districts may need to change to conform to 2010 redistricting requirements.

To do so, we divided the state's 2010 population by 27 to obtain New York State's ideal apportionment target population of 717,707 people. We then compared each district's 2010 population to that value. The map below shows the result.

Districts shaded yellow are the closest in population to the target. Districts in red are smaller than the NYS target population by 10% or more. Based solely on population, these districts may be candidates for combination with others in order to reduce the number of districts in New York to 27.

Interestingly, the 2010 data indicate that even more Congressional districts in the downstate region are significantly under the ideal target population than in western New York. If those charged with redistricting choose to eliminate a seat both from downstate as well as upstate, it remains to be seen whether that district would come from New York City or Long Island. The population of the 16 existing districts spanning Long Island's eastern end through the Bronx contained just over 10.7 million people in 2010. Divided by the target district population of 717,707, this is only enough population to support 15 districts. (The red districts in the map below are likeliest to be merged with others in order to have enough population to meet the target size.)

Click to download high-resolution map (PDF)

CUR Census 2010 - NY congressional districts map







New York State Legislature

By 2012, the New York State and Assembly will be redistricted. How the lines are drawn -- and whether the new districts tend to concentrate or disperse populations that tend to vote Republican or Democrat, among other characteristics -- will have a substantial impact on state policies for the next 10 years, and for the next round of redistricting in 2021-22.

Based on the state's 2010 population of 19,378,102 people, the "ideal" (or average) size of a State Senate district would be 312,550 people (assuming the number of Senate districts remains at 62). In the State Assembly, the "ideal" (or average) size would be 129,187 people. In 2000, the average size of a State Senate district was 306,072 people, and the average size of an Assembly district was 126,510 people.

In order to gauge which regions of the state might gain or lose legislative districts, the Center for Urban Research mapped how far each district's 2010 population differs from the "ideal" size. In New York State, legislative districts within plus or minus 5% of the ideal size are considered acceptable from an overall population perspective. (There are other demographic considerations that need to be addressed in redistricting, but this analysis focuses on total population.)

The maps below show which districts are within 5% of the ideal size in the State Senate and the Assembly, and which ones have a population 5% or more, or 5% or less, than the ideal size. Districts shaded red have "too many" people relative to the other districts and would need to give up population to other districts. The districts shaded blue have too few people. Portions of them would need to be combined with others so that all districts are within +/- 5% of the target size.

State Senate - population changes but no regional district shifts?

In the Senate, there may not be much of a change at all. Although the map indicates that upstate districts may need to expand in order to "acquire" more population (leading to a shift in districts from upstate to downstate), the table below shows that regional district distribution may not need to change. In other words, each region's population (Long Island, New York City, and upstate New York) has enough population for the current number of districts in each area. Of course, the boundaries of individual districts will need to grow or shrink in order to come within +/- 5% of the ideal population. But upstate may not need to lose a seat(s) to accommodate downstate's population growth.

However, the number of districts per region will be contingent upon the size of the redrawn districts. The maximum size a Senate District can be is 328,178 people (312,550 + 5%); the minimum size is 296,923 (312,550 - 5%). For example, if every upstate district was of the larger size, that region would only have 25.5 Senators (i.e., it would lose at least one seat). If the districts ended up all of the smaller size, upstate would gain a seat (28.2 districts). This is an important consideration, given the +/-5% leeway with redrawing Senate and Assembly seats (compared with Congress, whose districts have to be virtually identical in population).

CUR Census 2010 - NY legislative redistricting chart

Click to download high-resolution map (PDF)

CUR Census 2010 - NY senate districts map







State Assembly - NYC losses, suburban gains?

In the Assembly, it appears that district lines may need to redrawn so that Long Island and the upstate region each gain a new Assembly district at the expense of New York City's districts. The table above provides the population counts, and the map below is consistent with that analysis.

CUR Census 2010 -NY assembly districts map







Cautionary Notes

This analysis is based on several assumptions that may change. Due to concerns from officials in New York City about possible undercounting by the Census Bureau, it is possible that the Bureau's official counts may be challenged. If a challenge is brought successfully, it may change the official population distribution.

Also, the analysis also does not account for a change in how New York's prison population will be counted for the purposes of redistricting (note that this only applies to state Senate and Assembly, not Congressional districts). In 2010, NY Governor Paterson signed a law (Chapter Laws of 2010, Chapter 57, Part XX) to require New York's redistricting task force to reallocate prison populations back to verifiable “homes of record” where the prisoner resided prior to his or her incarceration for state legislative and local governmental redistricting. The task force will obtain the prison count population data from the New York State Department of Correctional Services. Until then, we are not able to accurately estimate the ideal district size based on this revised approach to counting the prison population.

Finally, we assume (as noted above) that the total number of State Senate and Assembly districts remain the same (62 Senate seats, 150 Assembly seats). And we assume that district boundaries in the next round of redistricting will respect the regions (LI, NYC, upstate) used in the tables above. If, for example, a Long Island Senate district is allowed to extend into New York City, or vice versa, the analysis above would need to change.