The majority of air traffic comes through Denver International Airport, located 42 miles from Boulder and served by 23 passenger airlines. The new Northwest Parkway toll road connects the airport with Boulder, and costs $5.25 each way.
Hourly shuttle service and limousine service from the airport to Boulder is also available. Jefferson County Airport is located 11 miles from Boulder, and provides commuter air service, as does the Boulder Municipal Airport, located three miles northeast of the central business district.
Interstate 25, Colorado's major north-south highway, runs just to the east of Boulder. The Boulder-Denver Turnpike connects the two cities, and I-70 at Denver provides links east and west. Other major highways include U.S. Highways 36, 52, 93, and 287.
Major thoroughfares in the city include Broadway and Twenty-Eighth Street, running north and south, and Iris Avenue, Canyon Boulevard, Arapahoe Road, and Baseline Road, all running east and west. The Regional Transportation District (RTD) operates a fleet of buses serving the metropolitan area. The HOP line makes 40 stops in a loop throughout central Boulder, while the SKIP lines runs north and south along Broadway; other RTD bus lines in Boulder are the JUMP, DASH, BOUND, and STAMPEDE.
Bicycling is extremely important to travel in Boulder, as 10 percent of its resident ride bikes on a regular basis. Bicycle paths parallel all major traffic arteries, and total more than 200 miles. A fleet of 150 bright green bicycles, part of the Spokes for Folks "Green Bikes Program," are provided free to residents as loaner vehicles to be shared by all residents of the city. The Annual Walk and Bike Week encourages commuters to get out of their cars and either pedal or walk to and from work. Local businesses, such as restaurants and bicycle mechanics, offer free incentives to participants.