Using data collected from the Census Bureau, NPR has created a handy little interactive map allowing you to see what the most common professions are by state and by year.
Not surprisingly, truckers currently dominate the map as they are essentially needed for everything, and driving is yet to be fully automated. Another interesting commonality among states is the amount of secretaries listed — that is, until the 1990s, presumably because personal computing became the norm. Before secretaries, machine operators were extremely prevalent, but as automation came for the secretaries, factory jobs were increasingly outsourced to Asia — interesting.
It really makes you wonder what the map would look like if you could extend its timeline into the 2040s. Any guesses? I think the most common job is going to be secretary to a robot.