“Brooke Amendment” is the common name for section 213 (a) of the Housing and Urban Development Act of 1969 that was sponsored by Senator Edward Brooke III (R-MA), which capped rent in public housing projects at 25% of tenant's income. It amended section 2(1), paragraph two, of the US Housing Act of 1937, and was enacted on Christmas Eve, 24 December 1969. The Brooke Amendment became the first instance of the benchmark to measure housing affordability, which became known as the "30 percent rule of thumb" in 1981 when the 25 percent cap was raised to 30 percent of tenant income.