Route 66

Key bus routes of the Massachusetts Bay Transportation Authority (MBTA) system were the 15 routes that had high ridership and higher frequency standards than other bus lines, according to the 2004 MBTA Service Policy. Together, they accounted for roughly 40% of the MBTA's total bus ridership. These key bus routes ensured basic geographic coverage with frequent service in the densest areas of Boston, and connected to other MBTA services to give access to other areas throughout the region.