Giving Relief to American Communities in Emergencies Act or the GRACE Act This bill extends authority through FY2022 for the Department of Transportation (DOT) to distribute formula funding for certain programs using the 2000 Census for areas that lost their urbanized area designation because their population fell below 50,000 after the 2000 census as a result of a major disaster. Upon request by a state in which an urbanized area that experiences a disaster-related population decrease is located, DOT may elect for purposes of the public transportation emergency relief program to (1) use the population of such area, as determined in the decennial census before the most recent decennial census; and (2) continue to treat the area as an urbanized area.