The American Community Survey (ACS) was developed to replace the decennial census "long-form" information. The ACS estimates are produced annually and were first administered in 2005. Similar to the "long form", the ACS collects detailed socio-economic information but interprets it differently. The primary purpose of the ACS is to describe characteristics over a period of time, not to provide point-in-time counts.
The ACS currently produces two data sets: one-year (countywide) and five-year (countywide and smaller geographies) estimates. Data users should not mix these two data sets, and when feasible, use the most current ACS data set that supports the smallest geography being analyzed. Data users also need to draw conclusions carefully about the differences between ACS estimates. The margin of errors (MOE) is highly recommended to be examined to determine the statistical differences.
