Catching up with the latest Census releases
The U.S. Census Bureau, which releases some sort of data nearly every week, released its largest trove of data in a decade earlier this week with the 5-year estimates for the American Community Survey. Next week, it will release the first batch of results from the 2010 Census conducted earlier this year.
Here’s a quick rundown of what’s important in each release:
American Community Survey 5-year estimates
These are estimates of all types of demographic and sociological information for every part of the country, from states all the way down to the smallest census-level geography called a block group. The American Community Survey is sent to 3 million households each year. From those surveys, the Census Bureau can perform estimates in several categories.
- To look up your community in the latest ACS estimates, check out the American Factfinder tool.
This latest 5-year ACS release covers 2005 to 2009. The Census Bureau has been releasing similar information, in either 1-year estimates or 3-year estimates, for larger levels of population since 2007. For example, 1-year ACS estimates cover places with more than 65,000 people. The 3-year estimates cover places with more than 20,000 people.
Since this is a survey, and not an actual count like the decennial census, these data points come with margins of error, much like you’d see margins of error in an election poll. The Census Bureau has a lot of technical documentation on how it figures the estimates, but what you need to know is that the smaller the population area, the higher the margin of error.
For example, the margin of error for the percentage of high school graduates in Wellston, Okla., is plus/minus 10 percentage points. For Oklahoma City, the same category has a margin of error of plus/minus 0.5 percentage points. That’s because Wellston has a population of about 1,000 people, and Oklahoma City has about 546,000 people. Fewer ACS surveys went to Wellston residents than they did to residents in Oklahoma City, but the Census also takes confidentiality into account.
Here’s how the Census Bureau describes it:
To maintain confidentiality, the Census Bureau applies statistical procedures that introduce some uncertainty into data for geographic areas with small population groups.
Despite these limitations at really small places or units of geography, the ACS data is still useful to policymakers, academics and the public. The real benefit from having this ACS data will come in the next few years, when we have a baseline against which we can compare new data releases.
The New York Times released a slick-looking interactive map showing some of the latest ACS estimates: Click for an interactive version
The newspaper, with the help of Social Explorer, plotted various demographic estimates for each Census tract in the country. They used what’s called a dot-distribution map, which spaced out the dots randomly within the area of that particular tract. While it’s visually compelling, that can cause dots to show up in strange places, like the middle of a lake.
Source: The New York Times
2010 Census Apportionment/State Population data
This is the first batch of information from the 2010 census. It will be limited to population counts for the nation and states. By law, this data has to be reported to the president by Dec. 31.
The census uses this information to do apportionment, the allocation of congressional seats in the House of Representatives. Unlike 2000, when Oklahoma lost a congressional seat, there will be no change in the number of House seats this year.
The number of House seats–which now stands at 435–has been set since 1911. The first House of Representatives had just 65 seats in 1787. That rose to 105 after the 1790 Census.
For more on apportionment, check out this video from the Census Bureau:
Here’s some more information on previous population totals by state: Click for an interactive version
–Paul
Written by Paul Monies
Follow @pmonies
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