The name info may be in one of the other responses on the forum, but briefly...the original name was MacGiollaEoin (means follower of St. John).Say it fast with a bit of an accent and you can see how a British ear might hear it as McAloon.Later it was Anglisized to Monday.Some branches have kept that name, but most went back to McAloon upon arrival in the US or after Independence.
As for how many McAloons there are, there are a lot more than most of us thought.Just run the name on several search engines and you come up with some in every state, well,almost.Didn't see any in North Dakota or Alsaka. Of course, those of us with married names are invisible in such a search.
AS you can see from the forum, there seems to be 2 branches, one from Ireland and one from Scotland. Haven't worked our way back to where they meet yet.
Do you know where your ancestors came from?
I have been hoping someone would start a McAloon Web site.Any volunteers?