In 1980, due to high inflation, the federal government passed a special law that allowed national banks to ignore state usury limits and pegged the rate of interest at a certain number of points above the federal reserve discount rate. In addition, specially chartered organizations like small loan companies and installment plan sellers, such as car financing companies, have their own rules.
The 1978 case Marquette National Bank v. First of Omaha Service Corp. unanimously held that nationally chartered banks may charge the highest rate allowed in the bank's home state. This is why so many banks are located in states like Delaware and South Dakota, which have very liberal or nonexistent usury laws. So even if you live in a state that has a very low usury limit, it typically has no bearing on the interest you pay on your credit card.
https://www.upcounsel.com/lectl-state-interest-rates-and-usu...
In 1980, due to high inflation, the federal government passed a special law that allowed national banks to ignore state usury limits and pegged the rate of interest at a certain number of points above the federal reserve discount rate. In addition, specially chartered organizations like small loan companies and installment plan sellers, such as car financing companies, have their own rules.