Regulation Q
Regulation Q capped interest rates on domestic demand deposits (basically savings and checking accounts [...]). This was designed to (a) discourage local banks from depositing their money with big banks, and instead to lend local locally, and (b) limit competition among banks, thereby ensuring the stability and survival of those same local banks.
mentioned as one of the best-
known capital controls implemented in the US during the Long Boom
the "local locally" part is, I think, a typo in the original