You're not likely to find many obviously Polish ethnic around here for sure...
most originated as German, Irish or Scot and good portion don't even know that much about their own bloodline (though ironically the first "real" Poles I ever saw were 3rd generation kids in my local high school. They were husky, a bit dark skinned, white haired with ice eyes and bushy black brows- the whole stepstool family looked that way.)
I'm presently in the TriCounty foothills 60 miles from either Asheville or Charlotte (aka Podunk ) downsizing the amount of junk my mom has so I can move her to me in Arizona. Luckily this State has only stolen 5 years of my life in total. I can't wait to get back home. I like some things here...but nothing keeps me. Least it's cheap so I can keep my house up while renting here. Heh ...so you don't like the wheeless trans-camero collections and porch appliances..awww.
link for humor only:
For Southeast- Raliegh, as mentioned, I have heard mentioned.
There are fair size Polish communities in Florida... mostly southern FL.
Memphis, and Nashville have sizeable portion -enough to have a deli (I wasn't searching Poles at time- I was searching for Euro delis; I am huge consumer of fine sausages and pickled items. I was at Ft Lewis).
I saw a Polish store when I was stationed in Alabama..but that was quite some time ago (80s)
The farrier school I wanted to attend in WV is near several polish communities like Wheeling (I was researching nearest catholic churches)
I can't really recall very many festivals therefore a representative ethnic communities of any size in the Carolinas except fake kitschey stuff along the seaboard tourist traps. A few Celtic based ones in Ashevile and Charlotte and Raleigh/Durham, there quite a few German ones that are long running including a few Oktoberfests throughout Carolinas. And of course Native American festivals.
Maybe immigrant Poles didn't like the humid southern states much? Or good farmland was already taken and no mining? If they had similar reason as Czechs.
I believe the previous suggestion of joining a Polish club would be the best way to connect you to other AmPoles but those are places to look : )
Really other than up north in obvious places like NY, Boston or Chicago:...where I stay clear of....brrr! you'll find some pretty big Polish (and czech) communities central like in Texas/Oklahoma then some spatter across places like Wisconsin/Nebraska. My fathers birthtown, Ennis even has a well known International Polka festival (czech origin). Festivals near Houston (polish) and Austin (Polish) as well. Texas is proud to have had the first Polish farming community (not first Polish ever -but specific community in 1854..a year before Polonia..lol)