The term “50-percent payment” means the payment that is the sum of the 50-percent share otherwise paid to a county pursuant to title II of the Act of August 28, 1937 (chapter 876; 
50 Stat. 875; 
43 U.S.C. 
1181f), and the payment made to a county pursuant to the Act of May 24, 1939 (chapter 144; 
53 Stat. 753; 
43 U.S.C. 
1181f–1 et seq.).