Bypass (road) - United States

United States

In the United States, bypass routes are a type of special route used on an alternative routing of a highway around a town when the main route of the highway goes through the town. The original designation of these routes were "truck routes" to divert through truck traffic away from the town, but the designation was changed to "bypass" in 1959-1960 by AASHTO. However, many "Truck" routes remain where the mainline of the highway is prohibited for trucks.

In a few cases, both a bypass and a business route exist, both with auxiliary signs (i.e. U.S. Highway 60 in Lexington, Kentucky). Bypass routes are less common than business routes. Many of those that existed before the era of Interstate highways have lost their old designations. For example in Missouri, the old bypass route of U.S. Highway 71 to the east of Kansas City, Missouri was decertified as Interstate 435 supplanted, the remainder that existed as suburban surface route becoming Missouri State Highway 291; around St. Louis, Missouri, what had been Bypass U.S. Highway 50 was absorbed into a diversion of U.S. Highway 50 from Interstate 44 and Interstate 64.

In the Interstate highway system in the United States, bypasses and loops are designated with a three digit number beginning with an even digit. Note, however, that this pattern is inconsistent enough that, as in greater Des Moines, Iowa the genuine bypass is the main route (in that case, Interstate 35 and Interstate 80, and the loop into downtown Des Moines is Interstate 235; or as in Omaha, Nebraska, where Interstate 480 traverses their downtown area, which is bypassed by Interstate 80 and Interstate 680 and also Interstate 95 which goes through Philadelphia, Pennsylvania and Interstate 295 is the bypass around Philly which goes into New Jersey.

Another meaning of the term bypass route (usually simply called a bypass) is a highway that was constructed to bypass an area that is often congested with traffic. This includes Interstate highway beltways and U.S. Highways constructed to circumvent downtown areas. Examples of these are U.S. Route 60 bypassing Williamsburg, Virginia, U.S. Routes 31 and 20 bypassing metro South Bend, Indiana (the St. Joseph Valley Parkway), and Interstate 75 bypassing Tampa and St. Petersburg, Florida. These bypasses usually carry mainline routes rather than auxiliary "bypass" routes.

The first bypass route in the United States was completed in 1958, as Alabama State Route 210 (Ross Clark Circle) in Dothan, Alabama.