Two Population Counts by Census Bureau, Two Different Numbers: The Gap Between City 2009 Estimates and 2010 Census

Every year the Census Bureau conducts population estimates for various geographic areas. The Bureau considers the population count from the previous decennial census as a starting point and then uses local administrative records to estimate how the population has changed. These records include county tax return data and statistics on births and deaths. The Bureau then uses housing records of cities within a given county to estimate the county population’s distribution. The Bureau’s national decennial population count for 2010 was approximately 3 million people higher than its estimate in 2009. According to an article published by, a Pew Center on the States publication, this type of discrepancy is to be expected in a rapidly growing country. However, the 2010 decennial population count for the country’s 50th largest cities was 1.3 million lower than the Bureau’s 2009 estimate. Detroit’s decennial population count in 2010 was nearly 200,000 people below the 2009 estimate. Atlanta’s discrepancy was also drastic, with a 2010 decennial count falling below the 2009 estimate by almost 120,000 people. Omaha, Phoenix, Cleveland, Dallas, Miami, Houston, Chicago, and Mesa, Arizona all had counts at least 5 percent below the Bureau’s 2009 estimate.

Greg Harper, a Census Bureau demographer, points out that both Atlanta and Detroit challenged estimates earlier in the decade to increase their respective population counts. When cities do not agree with the Bureau’s estimates they are given an alternative formula to produce a new number. This formula relies on a number of conditions, one of which is a constant housing vacancy rate. The Pew Center on the State’s article proposes that this condition likely was not met by Atlanta and Detroit; both cities have struggled with the economically unfavorable housing markets. This may have skewed population estimates. Similarly, an article in the Atlanta Journal-Constitution found population estimates to have understated the negative consequences that the recession would have on Atlanta.
Others, such as demographer Jerome McKibben, find fault in the actual decennial population count of 2010, and not the 2009 estimate. McKibben has studied Atlanta and notes that the Bureau was not the only organization with elevated population estimates for Atlanta. McKibben proposes that there was an error in the decennial count, estimating that between 80,000 and 100,000 people in Atlanta were unacknowledged by the Bureau’s 2010 population count. According to McKibben, it is particularly hard for the Bureau to reach all residents of big cities because they often have large populations of immigrants and transitory inhabitants. According to the Pew Center on the States article, several cities including Detroit, Atlanta, Chicago, New York City, and Miami have discussed challenging the Bureau’s decennial count. The Bureau begins reviewing challenges on June 1, 2011.
The Census Bureau only considers challenges to the decennial census on three grounds: if a housing unit was counted in the wrong location; if boundary lines were erroneous; or if a processing mistake resulted in the omission of an address. According to the Pew Center on the States article, cities would need to present a specific error made by the Bureau in order to pose a legitimate challenge. A city’s hypothesis that it may have been undercounted does not meet this criterion.
A possible undercount of a city’s population means that it will receive less federal aid than the amount to which it may be entitled. In addition, the stakes are particularly high because the decennial population count determines the U.S. congressional and state legislative redistricting processes. Redistricting only happens once a decade, and so the districts determined by the 2010 Census counts will remain unchanged until the 2020 Census. Mayor Mike Bloomberg of New York City released a statement confirming his plan to challenge the Census count. While he acknowledges that the count used to determine the 2010 redistricting cannot be changed, Mayor Bloomberg stresses that a successful challenge would result in a higher baseline population for the Bureau’s population estimates leading up to the 2020 decennial count ensuring that the city receives the federal aid to which it is entitled.

Posted by JVSF
SSDAN Office

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