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Cornell Program on Applied Demographics

Census 2020 results

Data and analyses for New York from the data products as they are released over time by the U.S. Census Bureau

  • Introduction
  • Disclosure Avoidance System
  • Geography
  • Apportionment
  • Redistricting (PL94-171)
  • Future releases
  • Data Quality


External resources:


The decennial census has been conducted in years ending in "0" since 1790, as required by the U.S. Constitution. Article I, Section 2 states that:

"Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers . . . The actual Enumeration shall be made within three Years after the first Meeting of the Congress of the United States, and within every subsequent Term of ten Years, in such Manner as they shall by Law direct."

Use of Census Data

Beside determining how many representatives each state get, Census data is used for many other cases, for example:

  • Representation in State and Federal legislative chambers
  • Funding based on population counts and characteristics
  • Learn about the counts and characteristics of the residents in a community
  • Planning future resources
  • Business decisions
  • A base for population estimates estimates and projections
  • Source for research in demographic change and the social fabric
  • Denominators for health statistics
  • Etc.

2020 Census Data product

After the questionnaires are collected, the Census Bureau goes through a process of verification, unduplication and filling in the gaps. Before releasing the counts, the Census Bureau makes sure it doesn't release any personal sensitive information and runs the counts through the Disclosure Avoidance System. The Bureau releases different data products over time, each with more level of detail.

  • Apportionment data, release date April 26, 2021. This data contains total counts at the State level and determines the number of representatives in the House of Representatives.
  • Redistricting data (PL94-171), release date August 12, 2021. This data contains total counts, voting age and detail on race/ethnicity down to the Census Block level.
  • Demographic profiles, release date TBD. Overview of most important demographic characteristics for most governmental geographic areas (counties, cities, towns, places). Details to be determined.
  • Demographic and Housing Characteristics (DHC), release date TBD. A set of detailed tables with demographic information. The exact details are under development and depend on the ongoing development of the Disclosure Avoidance System for this product.
  • Detailed Demographic and Housing Characteristics (DDHC), release date TBD. Demographic information for detailed race categories and also additional data on household types and sizes. Details to be determined.

Many geographic boundaries are being confirmed and updated every ten year. The Geography tab contains links to the current geography boundary files.

Data Quality

During all the steps in the Census operation a lot of data is collected that can be used to quantify how well each process in the operation is going. Some of these metrics are used to measure the efficiency of the processes, and others can inform claims about the quality of the count.

Another way of gauging quality is comparing the Census counts with independent population estimates.

The Data quality tab contains links to analyses of data quality.

Disclosure Avoidance System (DAS)

External resources:

At the Census Bureau



The U.S. Census Bureau is required to do an “actual Enumeration” of all the people living in the U.S. every 10 years (U.S. Constitution, Article 1, Section 2). The bureau also is required to keep personally identifiable information confidential for 72 years (92 Stat. 915; Public Law 95-416). Title 13, U.S. Code, Section 9, provides the mandate for the bureau to not “use the information furnished under the provisions of this title for any purpose other than the statistical purposes for which it is supplied; or make any publication whereby the data furnished by any particular establishment or individual under this title can be identified; or permit anyone other than the sworn officers and employees of the Department or bureau or agency thereof to examine the individual reports (13 U.S.C. § 9 (2007)).”

The dual requirement for an accurate count and the protection of respondents and their data creates a natural tension: The more accurate (and therefore usable) the reported data is, the easier it may be to identify individual responses. And yet, as the raw data is altered before being reported (to protect confidentiality), the less usable the publicly released data is.

Differential Privacy

The Census Bureau also added some obscured some of the data as a way to avoid disclosure.

In the second half of last decade the Census Bureau announced that they decided to develop new DAS tools for the 2020 Census. These new tools are based on the concept known in scientific and academic circles as “differential privacy.” It is also called “formal privacy” because it provides provable mathematical guarantees, similar to those found in modern cryptography, about the confidentiality protections that can be independently verified without compromising the underlying protections.

“Differential privacy” is based on the cryptographic principle that an attacker should not be able to learn any more about you from the statistics we publish using your data than from statistics that did not use your data. After tabulating the data, we apply carefully constructed algorithms to modify the statistics in a way that protects individuals while continuing to yield accurate results. We assume that everyone’s data are vulnerable and provide the same strong, state-of-the-art protection to every record in our database.

The consequences of the new DAS for data use

Over the last few years, the Census Bureau developed the new DAS, kept stakeholders informed and solicited feedback on several iterations of the system.

In June 2021 the Census Bureau settled on final settings of the system. The acting Director wrote in a blog post about consequences of the DAS on the redistricting data:

With these parameters, some small areas like census blocks may look “fuzzy,” meaning that the data for a particular block may not seem correct. Importantly, our approach yields high quality data as users combine these "fuzzy” blocks to form more significant geographic units like census tracts, cities, voting districts, counties, and American Indian/Alaska Native tribal areas. Our calibration was designed to achieve acceptable quality thresholds for these levels of geography.

So, if you’re looking at block-level data, you may notice situations like the following:

  • Occupancy status doesn’t match population counts. Some blocks may show that the housing units are all occupied, but the population count is zero. Other blocks may show the reverse: the housing units are vacant, but the population count is greater than zero.
  • Children appear to live alone. Some blocks may show a population count for people under age 18 but show no people age 18 and older.
  • Households appear unusually large. For example, you may find blocks with 45 people, but only three housing units.

Though unusual, situations like these in the data help confirm that confidentiality is being protected.

Noise in the block-level data will require a shift in how some data users typically approach using these census data.

Instead of looking for precision in an individual block, we strongly encourage data users to aggregate, or group, blocks together. As blocks are grouped together, the fuzziness disappears. And when you step back with more blocks in view, the details add together and make a sharp picture.

In short: block level data is very fuzzy, but fuzziness should disappear in aggregates. Be careful with interpreting average household size as the system is not optimized to deal with this metric.

In August 2021 the Census Bureau also releases a demonstration product based on the same final settings, but applied to the 2010 Census. This allows for more insights in the amount of noise for different situations.

Impossible and improbable block counts in the 2020 redistricting file compared with 2010

Count% of allCount% of all
Non empty blocks250,070233,182
Households (occupied houses) and household population
Household population > 0, but occupied houses = 0Impossible in 201014,2766.1%
Household population < occupied houses (Persons per houshehold < 1)5,7642.5%
Household population = 0, but occupied houses > 01,8340.8%
PPH > 10530.0%4,5101.9%
Youth only
Only 0-17210.0%2,8081.2%
Without GQ and only 0-1710.0%2,7951.2%


External resources:

At the Census Bureau

Apportionment is the process of dividing the 435 memberships, or seats, in the House of Representatives among the 50 states based on the population figures collected during the decennial census.

Apportionment is based on the number of residents in each state and counts of overseas population that are assigned to each state.

In 2020 the resident population of New York was 20,201,249 (19,378,102 in 2010) and the overseas population that was assigned to New York was 14,502 (42,953 in 2010). The growth of the New York population didn't keep up with the total growth of the US population and the NY share declined. The New York 2020 count was just not enough to hold on to 27 seats in the House of Representatives.

New York Resident population as reported in the 2020 Apportionment numbers and previouses Censuses

New York202020102000199019801970
Resident Population20,201,24919,378,10218,976,45717,990,45517,558,07218,236,967
Percent Change4.2%2.1%5.5%2.5%-3.7%8.7%
Share of US population6.1%6.3%6.7%7.2%7.8%9.0%
Number of Seats262729313439

Redistricting (PL94-171)

External resources:

At the Census Bureau


On August 12, the Census Bureau released the Public Law 94-171 data, better know under the ame redistricting data. The primary use of this data is drawing new legislative districts that will give everybody equal representation. The August data release will also provide the first look at the demographic characteristics of the nation by state, county, city, all the way down to the census block level, including:

  • Race and ethnicity.
  • Population 18 years and over.
  • Occupied and vacant housing units.
  • People living in group quarters like nursing homes, prisons, military barracks and college dorms.

Redistricting data for New York

The data released in August was in a 'legacy' format. We transformed this data and produced a number of Excel workbooks and geodatabases that contain data from the redistricting data and similar data from Census 2000 and Census 2010.

All PL data in Excel format

Excel sheets with all of the raw data:

2020 PL data compared with 2010 and 2000

Excel workbooks for different levels of geography (select number of variables) - Coming soon

* These workbooks contain revisions that were the result of the Count Question Resolution program. Only totals are revised, so when comparing totals over time, using the revised numbers are recommended. Especially in 2000 there were quite a few corrections because Group Quarters were originally tabulated in the wrong block. The number of revision in 2010 was much smaller. Download 2000 CQR revisions. Download 2010 CQR revisions.

Select results

Percent change in county population between 2010 and 2020

Population by Economic region

Population count Change (count) Change (%)
 4/1/20004/1/20104/1/2020 2000-20102010-2020 2000-20102010-2020
New York State18,976,82119,378,10220,201,249 401,281823,147 2.1%4.2%
Capital District1,029,9271,079,2071,106,088 49,28026,881 4.8%2.5%
Central NY780,716791,939785,114 11,223-6,825 1.4%-0.9%
Finger Lakes1,199,5881,217,1561,222,868 17,5685,712 1.5%0.5%
Long Island2,753,9132,832,8822,921,694 78,96988,812 2.9%3.1%
Mid-Hudson2,179,1892,290,8512,398,150 111,662107,299 5.1%4.7%
Mohawk Valley497,935500,155483,358 2,220-16,797 0.4%-3.4%
New York City8,008,6548,175,1338,804,190 166,479629,057 2.1%7.7%
North Country425,859433,193421,694 7,334-11,499 1.7%-2.7%
Southern Tier657,297657,909640,036 612-17,873 0.1%-2.7%
Western NY1,443,7431,399,6771,418,057 -44,06618,380 -3.1%1.3%

Change in population by Economic region for the major race/ethnicity categories

Change 2010-2020 (count) Change 2010-2020 (%)
RaceTotalNon Hispanic WhiteNon Hispanic BlackNon Hispanic AsianHispanic TotalNon Hispanic WhiteNon Hispanic BlackNon Hispanic AsianHispanic
New York State823,147-705,340-24,835510,135531,110 4.2%-6.2%-0.9%36.3%15.5%
Capital District26,881-62,5268,88519,91519,813 2.5%-6.9%12.7%69.0%46.5%
Central NY-6,825-53,3185,8756,59610,468 -0.9%-7.9%10.8%40.1%40.8%
Finger Lakes5,712-63,5383,3668,54125,511 0.5%-6.5%2.8%31.2%37.0%
Long Island88,812-199,25311,06276,331147,790 3.1%-10.2%4.5%50.3%33.5%
Mid-Hudson107,299-118,42414,02219,951128,248 4.7%-7.8%5.8%21.0%32.7%
Mohawk Valley-16,797-45,1891,7234,3268,013 -3.4%-10.2%9.9%51.5%37.1%
New York City629,057-3,048-84,404345,383154,274 7.7%-0.1%-4.5%33.6%6.6%
North Country-11,499-28,028-4657293,353 -2.7%-7.2%-3.2%18.2%25.3%
Southern Tier-17,873-55,8112,9755,1848,496 -2.7%-9.5%14.1%27.5%47.0%
Western NY18,380-76,20512,12623,17925,144 1.3%-6.7%8.7%85.6%44.4%

Change in population by Economic region for voting age and non voting age

Change (count) Change (%)
Age groupTotalVoting age (18+)Non voting age (0-17) TotalVoting age (18+)Non voting age (0-17)
New York State823,1471,034,962-211,815 4.2%6.9%-4.9%
Capital District26,88142,730-15,849 2.5%5.0%-6.9%
Central NY-6,82511,758-18,583 -0.9%1.9%-10.4%
Finger Lakes5,71231,714-26,002 0.5%3.4%-9.5%
Long Island88,812149,664-60,852 3.1%6.9%-9.1%
Mid-Hudson107,299120,666-13,367 4.7%7.0%-2.4%
Mohawk Valley-16,797-8,251-8,546 -3.4%-2.1%-7.9%
New York City629,057657,026-27,969 7.7%10.3%-1.6%
North Country-11,499-3,351-8,148 -2.7%-1.0%-8.6%
Southern Tier-17,873-2,596-15,277 -2.7%-0.5%-11.1%
Western NY18,38035,602-17,222 1.3%3.3%-5.7%

Future releases

No final decisions have yet been made as far as timeline and final content of future releases. The plan is to release:

Last modified: September 2, 2021