National Transit Workforce Training Act of 2020 This bill directs the Department of Transportation to establish a national transit frontline workforce training center (targeted to both rural and urban transit systems) and award grants to a nonprofit organization with a demonstrated capacity to develop and provide transit career ladder programs through labor-management partnerships and apprenticeships on a nationwide basis. The center must (1) be dedicated to the needs of the frontline transit workforce through standards-based training in the maintenance and operations occupations, and (2) develop and conduct training and educational programs for frontline local transportation employees engaged in government-aid public transportation work.