I know I'm probably missing something very basic, but I've been trying to join census block data together. The table contained within the block shapefile contains a field called GEOID10, which has concatenated the state, county, tract and block fields together. I have downloaded a table from the american factfinder that contains the total population for each block from the 2010 census and it contains a field called Id2 which has the same concatenated field as GEOID10. However, when I try to join the 2 together, ArcGIS won't give me Id2 as a field to base the join on when I choose GEOID10 as the field to use from the layer. Any idea why this is?
I'm using ArcGIS 10.5