; (B) has residential, commercial, and other nonresidential areas; and (C) is— (i) an urbanized area with a population of 50,000 or more; or (ii) an urban cluster with a population of— (I) not less than 2,500; and (II) not more than 50,000. (b) Grant program (1) Establishment The Secretary shall establish a grant program, to be known as the Transit to Trails Grant Program , under which the Secretary shall award grants to eligible entities for— (A) projects that develop transportation connectors or routes in or serving, and related culturally and linguistically appropriate education materials for, critically underserved communities to increase access and mobility to Federal or non-Federal public land, waters, parkland, or monuments; or (B) projects that facilitate transportation improvements to enhance access to Federal or non-Federal public land and recreational opportunities in critically underserved communities. (2) Administration (A) In general The Secretary shall administer the program to assist eligible entities in the development of transportation connectors or routes in or serving, and related culturally and linguistically appropriate education materials for, critically underserved communities and Federal or non-Federal public land, waters, parkland, and monuments. (B) Joint partnerships The Secretary shall encourage joint partnership projects under the program, if available, among multiple agencies, including school districts, nonprofit organizations, metropolitan planning organizations, regional transportation authorities, transit agencies, and State and local governmental agencies (including park and recreation agencies and authorities) to enhance investment of public sources. (C) Annual grant project proposal solicitation, review, and approval (i) In general The Secretary shall— (I) annually solicit the submission of project proposals for grants from eligible entities under the program