I don't believe it is possible via the Census API directly, as you cannot use a wild card for the county or request more than one county at a time for a state with block group level requests. However, I was able to pull all block groups for the state of Wyoming by using an array of county values for the geography. I'm not sure this would work for all states, as the number of counties may exceed some predefined limit. This is what that looks like in R: wy.geo=geo.make(state=56, county=c(1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45), tract="*", block.group="*") .