I have a massive file with county-level data from the 19th century. I'd like to georeference it, but I'm not sure what I need to do, as CartoDB isn't recognizing the county names through the 'Admin. Regions.' Do I need to import shapefiles and somehow connect them?
The CartoDB administrative regions geocoder doesn't include county data at the moment, so you'd need to upload a county dataset and merge it with your data table.
You can use the merge option in CartoDB, or you can use a SQL query in order to copy the geometries, such as:
UPDATE data_table SET the_geom = (SELECT counties_table.the_geom FROM counties_table WHERE counties_table.county_name like county)