From 1956 to 1986, America built the planet's largest public work, the National System of Interstate and Defense Highways. The interstate highway system transformed American life in ways both good and bad. It connected the nation but fostered alienating sprawl, spurred economic growth but blighted inner cities, bolstered some industries and destroyed others. Most of all, it committed us to automobility, to road trips, to car commutes, to a built world designed for the automobile and to an economy built on trucking. The interstate has become our circulatory system, and the blood that flows through it is oil.
Below, some notes toward mapping this marvel of modernity, this ecosystem disguised as infrastructure, this machine for both mobility and murder.
The highest point
At 11,013 feet, the 4-lane Eisenhower Tunnel is the highest point in the entire interstate system. Coming out of Denver, I-70 climbs slowly into the Rocky Mountains at the 7% grades required by the network's standards, then enters the tunnel, making crossing the Rockies almost unnoticeable in a normal car. The first interstate plan did not include a route through Colorado's Rockies; the Colorado governor immediately wrote Washington to insist that Colorado should have a transcontinental interstate. After extended lobbying, the state got its route, but I-70 is not the transcontinental route--or the swift route to Salt Lake City--the governor wanted. Rather, it dead-ends at I-15 in central Utah, halfway between Salt Lake City and Las Vegas.
The lowest point
Taking I-95 beneath the Baltimore Harbor, the Fort McHenry Tunnel, at 107 feet below sea level, is the lowest point in the interstate system. With 8 lanes in two bores, this tunnel sees extremely heavy traffic, as I-95 carries almost all traffic moving up the eastern seaboard.
The longest interstate
Stretching just over 3020 miles from Boston to Seattle, I-90 is the longest interstate highway. As it incorporates the MassPike, the NY Thruway, the Indiana Toll Road, the Chicago Skyway and parts of the Ohio Turnpike, all of which are tolled, it also has more toll miles than any other interstate. Tolls paid on the Indian Toll Road and the Chicago Skyway actually go not to Ohio and Illinois, but to the Spanish infrastructure company Cintra and the Australian Macquarie Bank, who have leased those roads from their states. When the interstate system was being discussed, many in Eisenhower's administration, including Ike himself, wanted the entire system to be tolled. Head of the Presidential Advisory Committee, Lucius Clay, assured them that there would be a "revolution" in Western states if the freeways were tolled. All of the western parts of I-90, including this section near the Badlands of South Dakota, remain free.
The longest exitless stretch
West of Salt Lake City, I-80 enters one of the least populous areas the interstate highway system serves. On a gravel and dirt substrate, straight as an arrow, it crosses the Great Salt Desert, including the intense, white emptiness of the Bonneville Salt Flats. For about 120 miles there are no towns, and few exits have services. Between Knolls and Wendover, a distance of 40 miles, there is no exit--the longest stretch without an exit in the entire system. If you miss Wendover, you have to drive 80 miles to get there again. And believe me, it's worth it.
The first interstate
A stretch of I-70 just west of Topeka bears a sign proclaiming it the first opened section of the National System of Interstate and Defense Highways. The road was already underway when the Federal Aid Highway Act of 1956 was passed, which is how it became the first completed part. It didn't hurt that this was the route to Abilene, Eisenhower's childhood home.
The first, again
Missouri also lays claim to the first section of interstate. Here, just west of the bridge over the Missouri River on I-70, a sign marks the first section of highway to be authorized under the Federal Aid Highway Act of 1956.
The most scenic stretch
There is in fact an official most scenic stretch of the interstate highway system. The Mountains to Sound Greenway, a roughly 100-mile section of I-90 between Thorp, Washington and Seattle, is the only part of the interstate system that has been officially included in the National Scenic Byways program. All the rest of the Scenic Byways are two-lane highways. Here, I-90 passes through Snoqualmie Pass, suspended in the stunning boreal landscape of Washington.
The greenest highway
Many people might argue that, in spite of the Mountains to Sound Greenway's scenic designation, I-70 through Glenwood Canyon is actually the most scenic stretch of interstate. When it was completed in 1992, the 12 and half mile stretch of freeway was touted as having been built to the highest standards of ecological conservation, and designed to enhance its natural surroundings, not transgress them. Passing between retaining walls painted to resemble the canyon's natural cliffs, the highway includes 39 tunnels and bridges to keep the road from ruining scenic vistas and canyon floors.
The greenest, continued
Zooming through Glenwood Canyon on I-70, it certain offers one of the most spectacular views to be had from the interstate. The rest areas offer access to hiking trails, and an excellent bike trail accompanies the freeway. When you get off the highway and get down on the canyon floor however, the interstate is not exactly low-profile. Activists fought the freeway from the beginning; singer John Denver threw a rock across the canyon in one early protest. The view from below both shows the highway's impressive engineering, and hints at how much was sacrificed to it.
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