My understanding was that daily milkmen went out at about the same time that refrigeration became popular, in the first half of the century. After all, why have the extra cost if milk will now last until you go to the store in a couple days.
In popular culture, though, milkmen stuck around through the sixties at least (this question was prompted by my seeing one on the Dick Van Dyke show.) Was this a holdover just of popular culture, or did milkmen actually survive refrigeration for a while, and if so, why?
hi! not discouraging more thorough input on this one, but you may be interested in these previous discussions
suggests pasteurization What was the U.S. milk delivery industry like in the mid 1900s?
a more general discussion Why was home milk delivery common in 20th century America, but home grocery delivery not generally available till much later?
Milkman delivery ceased about the early 1960's in the west U S anyway.The increase of Supermarkets and their volume buying meant greater savings to the consumer. Increased cost of fuel and maintenance also contributed to the demise of daily milk delivery and the consumer bought the fuel to get to the Supermarket. Our milkman was a cool guy and he would let me ride his truck for about a quarter of a mile to my house on hot days (90 + degrees many days) and his truck was refridgerated of course.