(There are still several destinations that are priced below their moving averages. The Southwest Sale has ended, but you may be able to make use of these remaining fares on competing airlines.)
Most domestic carriers have round-trip flights to/from various destinations in the USA at a discount today for $77-$185, NONSTOP or with a connection. Dates vary, use the linked calendar. American and Southwest are mostly on Tuesdays, Wednesdays, and Saturdays. United has better weekend availability. Origin/Destination reversible.
This list intentionally excludes fares on LCC Breeze/Allegiant/Frontier/Spirit.
For Southwest fares, you may need to plug-in the coupon-code “BDAY”. You should be able to see the fares on the calendar, linked, without using the code.
There are other destinations available that are priced higher than this range and those may be worthwhile for some of the small remote airports that have stops and don’t usually go on sale. They aren’t part of this list since we’re focusing on the cheapest routes.