7 C.F.R. § 1940.575
(b) Basic formula criteria, data source and weight. See § 1940.552(b) of this subpart.
The criteria used in the basic formula area:
(3) State's percentage of National rural families with incomes below the poverty level. The data source for the first two of these criterion is the most recent decennial Census data. The data source for the third criterion is the 5-year data from the American Community Survey (ACS) or, if needed, other Census Bureau data. Each criterion is assigned a specific weight according to its relevance in determining need. The percentage representing each criterion is multiplied by the weight assigned and summed to arrive at a State factor (SF).
SF = (criterion No. 1 × weight of 33 1/3%) + (criterion No. 2 × weight of 33 1/3%) + (criterion No. 3 × weight of 33 1/3%)
[53 FR 26229, July 12, 1988, as amended at 80 FR 9877, Feb. 24, 2015]