The documentation below explains how these conversion files were created. Remember there are multiple instances of LOGRECNOs in these conversion files because the census tracts they represent are split into two or more districts. Starting with the conversion file, you need us the LOGRECNOs to lookup the data for each record and then mulitply the data by either of the share fields (POPSHARE or HUSHARE). Documentation: SF3 - 080 State-County-County Subdivision-Place/Remainder-Census Tract SF1 - 101 State-County-County Subdivision-Place/Remainder-Census Tract- Block Group-Block This conversion is built looking up a tract record (sumlev = 080) in SF3 with matching common fields for each block record (sumlev = 101) in SF1 and carrying along pop100 and hu100 and logrecno from both for the combined record. Then CD AD and SD assignment looked up for each block. The hu100 and pop100 from SF1 is then aggregated for each district to sf3 logrecno combination. Each district population and housing unit share of each sf3 080 logrecno is calculated by dividing the aggregated pop100 and hu100 by the sf3 pop100 and hu100. This results in a district to SF3 sumlev 080 logrecno conversion, weighted by either population or housing units (hu). Format of conversion files is as follows. Variable Start End Format Comment District 1 2 A2 '.' 3 3 LOGRECNO 4 10 A7 logical record number in SF3 S1POP100 11 16 F6.0 pop in piece POPSHARE 17 24 F8.5 pop in piece/pop in tract (080) S1HU100 25 30 F6.0 hu in piece HUSHARE 31 38 F8.5 hu in piece/hu in tract (080)