Upon request of the proper officer of the United States, together with the order of the board of supervisors of the county, the county treasurer shall deposit with the Federal Reserve Bank to the credit of the United States all money set aside by the board of supervisors under agreements entered into with the United States in accordance with the provisions of the Federal-Aid Highway Act and subsequent acts of like nature. The money shall be paid out by the proper fiscal agent of the United States pursuant to the agreements.