Denver spreads across the South Platte River valley with the Front Range on its western horizon, and two interstates cross near the middle of the city. I-25 runs north-south through downtown toward Fort Collins and Colorado Springs, and I-70 runs east-west across the north side, heading west into the mountains and east onto the plains. US 6, the Sixth Avenue Freeway, runs west toward Lakewood and Golden, US 36 heads northwest toward Boulder, and I-225 links I-25 in the southeast with I-70 through Aurora. C-470 and E-470 trace a partial beltway around the southern and eastern suburbs.
The Mousetrap, where I-25 and I-70 meet north of downtown, and the I-25 valley highway through central Denver are slow every rush hour. Colfax Avenue, Speer Boulevard, Colorado Boulevard, Alameda Avenue and Federal Boulevard carry heavy surface traffic, and the downtown street grid sits at an angle to the rest of the city, following the river. On winter weekends, westbound I-70 toward the ski areas backs up for miles, and the return trip on Sunday afternoon is often worse.
Denver International Airport sits far northeast of the city at the end of Peña Boulevard, a long, exposed run across open prairie where wind and blowing snow make a breakdown miserable. RTD light rail and commuter rail lines, including the A Line to the airport, fan out from Union Station, and buses cover the main corridors. Plenty of people still drive daily, and with mountain trips, snow and hail in the mix, Denver cars work harder than the city's sunny reputation suggests.
