Southwest Airlines offers 1-way fares on 100 routes nationwide with prices starting at $55. (Click on "Southwest Airlines" in the top line to see this sale.) That's $4 under last week's mention and the lowest price we could find for select routes by $9. This price is valid on flights departing from Las Vegas, NV, (LAS) with arrival in Los Angeles, CA, (LAX) on September 8. Book this travel deal by May 7 for travel from August 28 through October 29. Other notable fares:

Boston (BOS) to Baltimore (BWI) from $69

Fort Lauderdale (FLL) to Atlanta (ATL) from $76

Chicago (MDW) to Washington D.C. (IAD) from $89

see all available Southwest Airlines fares

All prices, dates, and booking details were valid at the time of publication.