I think that what spawned these bureaucracies in the first place was the expansion of the areas in which the Federal government was directly involved. Those were pretty limited in the 18th and for much of the 19th century. The 20th century, especially from FDR onwards, saw a huge expansion of government intervention and thus the creation of agencies to carry it out.
“The 20th century, especially from FDR onwards, saw a huge expansion of government intervention and thus the creation of agencies to carry it out.”
I can’t recall the guy’s name, but before FDR’s social programs somebody was calling on the government to give everybody (I think) $400. The plan was hugely popular and had been adopted in one form or another by FDR’s rivals who were garnering a disproportionate number of votes, thus threatening FDR’s base. FDR did them one better by creating a host of social programs that, on the surface, were designed to combat a depression where people were starving. (In reality, the results were the opposite of what was “intended.”) Politically, the give-sh*t-away-free political move was popular and got FDR reelected. Since there is always more to give away if FDR had been immortal he could still be president today.