2020 Census Allocation to 2010 Census Tracts

Because the 2020 Census relationship files released by the Census Bureau did not include population or housing unit percentage allocations, alternative methodologies to allocate population and housing units between 2010 and 2020 Census tracts were tested. The methodology selected by DRU was to use building footprints and residential parcels at the 2020 Census block level to allocate population and housing units. The conversion methodology employs a four-step process that uses dasymetric interpolation as the basis for the allocation calculations. The four steps consisted of:1. Blocks containing residential parcels and intersecting building footprints were allocated to the tracts that the combined shapes intersected (67 percent - 351,313 blocks) then,2. Blocks containing residential parcels, but no building footprints, were allocated to the tracts that the parcel shapes intersected (2 percent - 11,299 blocks); then,3. Blocks that did not contain residential parcels or building footprints were allocated to tracts by areal interpolation (30 percent - 157,071 blocks); and finally,4. Blocks allocated manually (<1 percent - 5 blocks). Users should be aware that the allocated 2020 population and housing unit counts cannot be considered official U.S. Census Bureau data or California Department of Finance data.