The concept of the daytime population refers to the number of people who are present in an area during typical business hours, including workers , children in school, people in hospitals or other short - term medical facilities, people temporarily staying in lodging facilities, and customers present at retail locations. This is in contrast to the "€œresident" population , which refers to people who reside in a given area and are typically present during the evening and nighttime hours. Information on the expansion or contraction of worker populations throughout a typical workday is important for a variety of community planning purposes. These purposes may include, for example, addressing transportation planning issues and disaster relief operations.

The Census Bureau first published daytime population estimates using Census 2000 data. The estimates from Census 2000 are limited to the location of workers in a typical workday. No adjustments were made to account for the time of day commuters worked inside or outside specified areas or geographies. Thus, the estimates from Census 2000 are more accurately described as commuter - adjusted population estimates rather than the more familiar concept of daytime population estimates.

This paper accompanies the release of the Census Bureau'€™s first commuter - adjusted population estimates based on the American Community Survey (ACS), and the first commuter - adjusted population release since that based on Census 2000. It summarizes commuter - adjusted population estimates for place s, minor civil divisions (MCDs) , counties, and states based on the 5 - year 2006 - 2010 ACS estimates. The Census Bureau produces 1 - year and 3 - year ACS datasets, but only the 5 - year datasets have a large enough sample to provide reliable estimates for smaller counties, MCDs, and places. The 2006 - 2010 ACS dataset was selected in order to provide a reasonable comparison with the Census 2000 estimates. The ACS - based estimates use the same methodology as the Census 2000 estimates.