One commenter suggested Federal reimbursement for land or other assets (such as mitigation bank credits) acquired for mitigation prior to contemplated use on a specific transportation project (and prior to Federal authorization for a project) would be financially and environmentally advantageous for States. Suitable areas for environmental mitigation are becoming difficult to locate within States and more flexibility to acquire these lands or obtain mitigation credits when they are available would make mitigation of future Federal projects easier as well as help to avoid unexpected increases in mitigation land costs. Under this proposal, a State would acquire land or other mitigation assets with State funds that would be held for mitigation for future and, at the time of acquisition, unidentified State and Federal projects. If the land or asset is used on a future Federal-aid project, the cost of the land or asset would become eligible for Federal reimbursement as part of the total cost of said future Federal-aid project, even though the mitigation land or asset was acquired prior to the date Federal-aid funds would be authorized for said future project. Federal law currently does not allow reimbursement of project costs incurred prior to the authorization of Federal funds.[347]