where did the term paddiwagon orginate??
“Paddy wagon” probably comes from “Paddy”, a slang term for an Irishman (because of the great number of Irishmen arrested and carried in the wagons). See this site. See also this related thread: Where did “black maria” come from
I though that the connection to the Irish was not the criminals, but the police themselves. Cop was one of only a very few respectable jobs that an undereducated Irish immigrant could hold in the 1800s, so many became just that. This is also the source of the association between bagpipes and police funerals.