40 U.S.C. § 14521

A State or political subdivision of a State is not eligible to receive benefits under this subtitle unless the aggregate expenditure of state amounts, except expenditures for participation in the Dwight D. Eisenhower System of Interstate and Defense Highways and local and federal amounts, for the benefit of the area within the State located in the Appalachian region is maintained at a level which does not fall below the average level of those expenditures for the State’s last two full fiscal years prior to March 9, 1965 . In computing the level, a State’s past expenditure for participation in the Dwight D. Eisenhower System of Interstate and Defense Highways and expenditures of local and federal amounts shall not be included. The Commission shall recommend to the President a lesser requirement when it finds that a substantial population decrease in that part of a State which lies within the region would not justify a state expenditure equal to the average level of the last two years or when it finds that a State’s average level of expenditure in an individual program has been disproportionate to the present need for that part of the State.