Protecting Infrastructure Investments for Rural America Act This bill modifies the definition of rural area that is used for the Rural Surface Transportation Grant Program and adds provisions for small communities.As background, the grant program supports projects that improve and expand the surface transportation infrastructure in rural areas. Eligible applicants for the grant program include states, regional transportation planning organizations, local governments, and tribal governments.For purposes of the program, the bill defines rural area as an area outside an urbanized area that has a population of 30,000 or less. Current law requires a rural area to be outside of an urbanized area with a population of over 200,000.The bill includes provisions for small communities (i.e., an area outside an urbanized area and that has a population of 5,000 or less). The bill sets the maximum federal cost-share at 90% for project grants carried out in a small community. The Department of Transportation (DOT) must use at least 5% of the program's annual funds to provide grants for projects in small communities. The bill also removes the prohibition against DOT using more than 10% of program funds for grants that are under $25 million.Further, program grants may be used for highway, road, bridge, or tunnel projects that would benefit the economic development or quality of life for citizens of the local community.The bill also specifies that the program's goals include the generation of economic growth and development in rural areas.