What is the origin of the term "paddy wagon"?

[Pop1]

@Loopydude

I could be wrong, but I thought this was a no-brainer:

You go to cities like Bawstin or Noo Yawk, and it’s almost a cliche to get arrested by Sgt. O’Malley or Fitzpatrick. Irish Americans have traditionally been highly represented in the police forces of major East Coast cities.

Back in the day, after Captain McGrath clubbed you over the head with a nightstick for drunken disorderly, he shoved you in, what else, the Paddy Wagon! Originally this was a horse-drawn wagon with bars and whatnot, and later moterized versions were used, just as they are today, for transporting some number of officers of the law to, and hauling away criminal suspects from, the scene. Since “Paddies” (not a term I would use in casual conversation around the Irish, as it is considered a derogatory epithet, at least in some contexts) were often driving these wagons around, it’s not a great leap that they came to be know as Paddy Wagons.

Sure, later on the Irish joined the police forces en masse. But when they first arrived, no force would have them. They were on the lowest rung of society at the time.
Take the scene near the end of Mel Brooks’ Blazing Saddles where the townsfolks are more than willing to share their town with the various ethnicities of the railway contstruction workers… except for the Irish.