High Risk Rural Roads Safety Grant Program Act of 2021 This bill directs the Department of Transportation to award competitive grants to local governments, Indian tribes, metropolitan planning organizations, and other public transportation authorities for projects to improve safety on high risk rural roads in the United States. Funds may be used for certain projects or activities to improve safety, including (1) road safety audits; (2) intersection safety improvements; (3) the installation of rumble strips or other warning devices; and (4) activities that improve the safety of pedestrians, bicyclists, or individuals with disabilities. At least $100 million of funding available to carry out the grant program must be set aside for Indian tribes.