Last working Atlantic in US?

I once read 1953, but that has to be wrong. I've seen photos from multiple railroads dated 1954. I assume that the actual end was later than that.

Since you don't specify, One of the PRR atlantics was operated by Strasburg in the early to mid 80's.

I'll echo jgallaway81. This is the one I remember. Rode behind it when I was younger during its time on the Strasburg R.R. The Atlantic type was always my dads favorite locomotive type.
http://railpictures.net/viewphoto.php?id=57327&nseq=9

I rode behind it along time ago, too They evne had PA passengre cars that matchhed.

I'm more partial to this view: http://railpictures.net/viewphoto.php?id=199287&nseq=6

And of course, if you search the youtube "archives" for PRR 7002, you'll get a host of videos such as this one: http://www.youtube.com/watch?v=hKWPXOmtCJ8

Getting this on the intended track...

What was the last Atlantic in regular US Class 1 service?

What was the last Atlantic in regular US shortline (non-museum/restored/etc) service?

For that type of request, I'd say you'd almost have to scoure teh records and see which engine was the last to have a report filed with the ICC

I'd be willing to wager a box of doughnuts it was the PRRs E-6s on the PRSL in south Jersey.

ex Budd man wrote:I'd be willing to wager a box of doughnuts it was the PRRs E-6s on the PRSL in south Jersey.

You are most likely right. The E-6s were used at least up to 1955 as my father took movies of them on the Cape May Branch at Tuckahoe,Rio Grande and Wildwood Jct in the summer of that year.
The E-6s while a fairly modern engine in many ways remained hand fired and with no power reversers to the end. I have heard personally first hand from more than one old PRSL engineers that they were very well liked engines and it was not unusual for an E-6 to be assigned to Shore trains consisting of 14 P-70s. They said it took a deft hand on the throttle to get the train started out of Broadway Station on Camden as the main line left there with a short but challenging little grade followed by a curve at Center Interlocking.