I mostly notice Sam Waterston from Law & Order pronouncing it this way. “Detective Logan’s a Mick. I’m a Mick sir. And if you don’t shutup, I’m going to lose control and throw you out of the rum.”
His Bio says he’s from Northern Mass, but I know several people from that area and I’ve never heard them pronounce “room” that way. Is it some upper-crust thing? Yale thing? Do any Dopers pronounce it that way? Just curious.
I think it’s more “r[shwa]m” than “rum,” FWIW. I know people who pronounce “roof” and “root” the same way.
My friend says that, and her family is from New Hampshire, although she has lived most of her life in Illinois (I can assure you it is not a midwest thing).
I think most Americans pronounce roof and root the same (except for the last two letters). I know I do, although I don’t pronounce room the way the OP describes.
I pronounce roof the same way as hoof, but I pronounce root the same as hoot. All my brothers do too, so I guess we picked it up growing up in the Midwest.
I agree that when Sam Waterston says it it’s more like the way I say “roof” and “hoof”, but I also pronounce rum the same way.
To listen to him saying it in the quote I used above go to this site and play “mick.wav”
I can’t remember which way I’m supposed to pronounce it. “Route” I say both “root” and “rowt,” “root” rhymes with both “foot” and “hoot,” and the same with “roof.” I usually say it to rhyme with “foot”… I think. “Room,” however, gets the “oo” sound.
As for the OP, the people I knew who pronounced room similar to “rum” were all from Buffalo, working class.
The results of the American Dialect Survey don’t seem to show any obvious clustering.
I’ve heard both forms in California and it doesn’t seem to matter where the people hailed from.
I wish I knew of some way to insert IPA characters into posts.
I haven’t seen the show, so I don’t know exactly what you’re talking about. This may or may not be helpful.
This is a simplification, but there are sort of three “u” sounds in Enlgish. I’ll try to pick words that have pronounciations that most people agree on.
First we have /u/, as in the word “who”, “you”, “moo” (like a cow), “oooo, i’m telling!” (little sister), etc.
Then there is the schwah-like /^/, as in “up”, “tummy”, and “under”
Finally we have /U/, as in “hood”, “could” (i don’t say the /l/, do you?), and “book”.
Most places I have lived, people prounce “room”, “roof”, and “root”, with /u/. I spent some time about an hour south of Chicago, and people instead used the vowel /U/. I have not noticed this pronounciation in the central east coast, the southwest, or the west coast (although on preview I see that BobT has). I have not spent much time in the southeast, northwest, or extreme northeastern US so I can’t comment about those places. Dooku, if you really want to know about how they say things at Yale and no one answers, you can bug me in the fall after I start there. I never thought of it as an upper crust thing, because Kankakee IL is most definately not upper crust.
PS. John Mace , I don’t think lissener was saying that it’s unusual that people pronouce “roof” and “root” the same way, but that for those two words people use the vowel that is questioned in the OP.
I don’t think the shortened vowel is a Massachusetts trait, either.
As a Mass. native, I’d use the same vowel (Ruken’s /u/) for “who”, “roof”, “root”, “route”, “room”, and “hoot”.
“Hoof”, “foot”, and “could” all get /U/.
I’m originally from MA, and the only thing I’d add (and it might just be me) is that “route” gets pronounced differently if it’s a verb. It’s “*Root * 66”, but it’s “Please *rowt * the red wire under the blue one”. After all, Cisco makes Rowters, not Rooters. 
My grandmother, born and raised in Bucks County, Pennsylvania (something like 30 miles north of Philadelphia), pronounced “roof” as “ruf”, and “food” as “fud”, etc.
Yes, that pronunciation sounds a lot like some of my Pennsy relatives.
I can hear my high school math teacher saying it “rum”. She was from southwestern Pennsylvania.
For me, from Southern Ontario, the vowels in “roof”, “root”, “hoof”, and “hoot” are all pronounced the same, Ruken’s /u/.
John Mace, I pronounce “route” and “router” in two ways, but differently than you describe. If it has to do with the rotating power tool used to cut grooves in wood, I say “rowt”; if it has to do with maps, paths, or networks, I say “root”.
I do! ‘Rufe’ and ‘Rute’. Is that what you mean?