Upon reauthorizing CDBG in 1978, Congress instituted a dual formula to strengthen controls on how money was spent and to better serve communities with different types of problems. A city's proportion of the overall CDBG allocation is either the average of the area's fractions of the US's total population, total poverty and total amount of housing overcrowding, or the average of the area's fractions of the country's total growth lag, total poverty, and total age of housing. Formula A typically benefits rapidly growing cities with high poverty that lack affordable housing. Formula B tends to benefit older cities with large amounts of old and deteriorating housing.