Denver... Frontier and Delta close?
 

I am flying on Frontier through Denver airport on a connection. I need to go by a Delta ticket counter. Are they in the same terminal or near each other?
Thanks!

DL is in terminal C, and F9 is in Terminal A. There is a subway that runs between terminals at mid-terminal. I'd budget 10 minutes to go each way between terminals.

Your other choice would be to go to the main terminal (thus exiting security). You have a choice of the foot bridge or the subway for that. DL and F9 are both at the East end of the main terminal.

In short, I would only try it if your layover is at least 1 hour.

See DEN's map for more info.

If you need a ticket counter, you're best bet may be to exit security as btr noted. Delta does have a customer service counter on the C Concourse (between gates 42 and 44), but I'm not sure how well it is staffed.

In the Jeppesen terminal, Delta's ticket counter is south of Frontier on the east side, smack dab in the middle of the terminal, next to Alaska.

Lastly, I'd highly recommend adding at least 15 minutes to btr's suggestion to be safe.

I was thinking of the time needed to get between A and C. Certainly if security is involved, add at least another 15-30 minutes.