23 CFR § 710.507 - State and local contributions.
(a) Credit for State and local government contributions. If the requirements of 23 U.S.C. 323 are met, real property owned by State and local governments that is incorporated within a project receiving financial assistance from the Highway Trust Fund can be used as a credit toward the grantee or subgrantee's matching share of total project cost. A credit cannot exceed the grantee or subgrantee's matching share required by the project agreement. The grantee must ensure there is documentation supporting all credits, including the following:
(b) Exemptions. Credits are not available for real property acquired with any form of Federal financial assistance except as provided in 23 U.S.C. 120(j), or for real property already incorporated into existing ROW and used for transportation purposes.
(c) Contributions without credit. Property may be presented for project use with the understanding that no credit for its use is sought. In such case, the grantee shall assure that the acquisition satisfied the conditions in 23 CFR 710.501(c)(1) through (6).