The Fed keeps lowering the thresholds (and they'll end up doing a lot more than that in the coming months; most of this won't be short-term credit, they'll switch it to long-term out of necessity):

"Fed expands muni-debt program to cover smaller cities, counties"

"The Federal Reserve expanded the scope and duration of the Municipal Liquidity Facility, a $500 billion emergency lending program aimed at providing short-term credit to state and local governments as they endure the economic fallout from the coronavirus pandemic. The U.S. central bank lowered the population thresholds under which counties and cities would be eligible to sell short-term debt to the facility. The new levels are at least 500,000 for counties and 250,000 for cities, down from 2 million and 1 million."

https://www.bondbuyer.com/articles/fed-expands-muni-debt-pro...