Population MICA contains population detail for Missouri, its 115 counties (114 counties plus the City of St. Louis, which is an independent city) and Eastern Jackson County, Independence, Joplin and Kansas City by sex for selected age groups. In addition, for years prior to 2001, race detail for the state and eleven areas with the largest minority populations is available. These eleven areas are: Boone County, Greene County, Jackson County, Mississippi County, New Madrid County, Pemiscot County, Scott County, St. Charles County, St. Louis County, St. Louis City, and Kansas City. For 2001 and beyond race detail was added for the additional counties of: Buchanan, Cape Girardeau, Cass, Clay, Cole, Dunklin, Jasper, Platte, and Pulaski.

For the decennial Census years (i.e. 1990, 2000, 2010, etc.) the April 1 Census counts are used. All other years use a July 1 mid-year point as their date of reference. Estimates for the decade of the 1990s were produced by the Department of Health and Senior Services (DHSS) after the 2000 Census was released. The 1991-1999 age distributions were based on the 1990 and 2000 endpoints. The US Census Bureau provided controls for population at the county and state levels. Population for 2001 and later years comes from the US Census Bureau in partnership with the Federal State Cooperative Program for Population Estimates.

Three other related notes: for 1990 the Modified-Age-Race-Sex (MARS) population numbers are used. For 2000, we have added in the population from a prison in DeKalb County that was erroneously missed in the 2000 Census. The under 1 population count for all years and geographies comes from resident live births in Missouri using the Missouri Vital Records system.

The race estimates for the ten counties, Kansas City and the state are compatible with previous 1990s era estimates in that each person in a county is assigned to one of three race groups (white, black, or other). The race estimates were derived from bridged estimates produced by the National Center for Health Statistics from Census 2000. For 2000 and later years, numbers were taken directly from NCHS while the 1990s era age distributions were developed by DHSS using Census controls.