The Foothill Gold Line Extension (also known as the Gold Line Foothill Extension) is an under-construction extension of the Metro Gold Line light rail corridor from its current terminus in Pasadena, California, east through the "Foothill Cities" of Los Angeles County into San Bernardino County. The plan is currently being implemented as two separate mass-transit projects, known as Phase 2A (Pasadena to Azusa) and Phase 2B (Azusa to Montclair).