23 U.S.C. § 126

(a) In General .— Notwithstanding any other provision of law, subject to subsection (b), a State may transfer from an apportionment under section 104(b) not to exceed 50 percent of the amount apportioned for the fiscal year to any other apportionment of the State under that section. (b) Application to Certain Set-asides.— (1) In general .— Funds that are subject to sections 104(d) and 133(d)(1)(A) shall not be transferred under this section. (2) Funds transferred by states .— Funds transferred by a State under this section of the funding set aside for a State under section 133(h) for a fiscal year— (A) may only come from the portion of those funds that are available for obligation in any area of the State under section 133(h); and (B) may only be transferred if the Secretary certifies that the State— (i) held a competition in compliance with the guidance issued to carry out section 133(h) and provided sufficient time for applicants to apply; (ii) offered to each eligible entity, and provided on request of an eligible entity, technical assistance; and (iii) demonstrates that there were not sufficiently suitable applications from eligible entities to use the funds to be transferred.