I got a question about PSAP today and thought it would be worthwhile to post to the CTPP listserv: To be short and sweet, PSAP is largely for TRACT and BLOCK GROUP definition for the 2010 Census. http://www.census.gov/geo/www/psap2010/psap2010_main.html There are probably other geographic areas that are also included. Bureau wants you to contact their regional office: http://www.census.gov/field/www/ However, you may want to contact your State Data Center (SDC) who may already have established lead agencies for different counties in your state. http://www.census.gov/sdc/www/ Elaine