We're seeing a lot of extremely low fares between the East Coast/Chicago and Southern California. Where fares normally start in the $200s, right now prices start from $29 one way. Most of these fares are on Spirit and offer flexible booking through May 31st, so it's best to book before then since there's no guarantee they'll extend this policy.
Cheap Coast-to-Coast Flights Timeframe: 1. Jul. 2020 - 31. Dec. 2020
This is a sample link. You can adjust your cities and dates after clicking through.