That may be, or may not be, depending on the terms, but the legal requirement is for significant agreement, by enough to get 3/4 of the states for an amendment, or 2/3rds to get a treaty ratified by the Senate.
Simi Valley attempted so separate from the city of Los Angeles a few years ago. The ballot measure agreed that Simi Valley would pay $680 million to Los Angeles in the first few years after the separation.
It was voted down, but was close.
That may show the way to a deal, or it may show that the people considering secession just don’t want it bad enough.
The US Constitution is silent on the issue of secession. Quit spreading lies you are acting like OBastard.
That couldn’t have been Simi. Simi is actually in Ventura County rather than LA county so I don’t see how it could have ever been part of the city of LA.