The 2007 MSSA Detail layer (developed during July 2009 - July 2010) is an update to the 2005 version. The 2000 Medical Service Study Area (MSSA) Census Tract Detail polygon layer represents all California census tract boundaries used in the construction of the 2000 MSSA Boundaries. Each of the state's 7,049 census tracts was assigned to a medical service study area, as identified in this data layer. The 2000 MSSA Census Tract Detail data is aggregated by OSHPD, to create the 2000 MSSA data layer. This layer is part of the Healthcare Atlas of California.The 2007 MSSA Detail layer (developed during July 2009 - July 2010) was developed to update fields affected by population change. The Claritas 2007 population data pertaining to total, group quarter, race, ethnicity, and age was used in the update. Some geometry updates were also included in this version. In July of 2010 updates were made to the poverty data to correct a miscalculation of poverty percentages and to remove "2007" from field names. The 2000 MSSA Census Tract Detail map layer was developed to support geographic information systems (GIS) applications, representing 2000 census tract geography that is the foundation of 2000 medical service study area (MSSA) boundaries.
California. Office of Statewide Health Planning and Development