​Most states set maximum limits on interest rates that lenders may charge on residential mortgage loans. In recent years several states have raised their usury ceilings, eliminated usury ceilings entirely, or adopted floating ceilings that change periodically as other interest rates change. Floating usury ceilings are intended to protect individual borrowers from unusually high interest rates while avoiding disruptions in the credit flow to home buyers and reductions in residential construction that can result when market interest rates approach or exceed usury ceilings. This paper evaluates whether floating usury rate formulas recently adopted by various states will avoid impeding the flow of credit to home buyers.