Control city

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This sign in Oklahoma City, Oklahoma lists control cities of Wichita, Kansas and Ft. Smith, Arkansas, for Interstate 35 and Interstate 40 respectively.

A control city is a city or locality posted on a traffic sign indicating forward destinations on a certain route. Signs indicating such cities are usually found at highway junctions to show where the intersecting road goes, or on mileage signs on longer routes.

The American Association of State Highway and Transportation Officials (AASHTO) has standardized all control cities used on the Interstate highway system in the United States. The published standard is not always followed, either because major destinations have since appeared that were not on the original list, or because of state highway departments' hesitancy to sign destinations in other states. An example is a sign on eastbound Interstate 10 near Palm Springs, California, which, though Phoenix, Arizona is the nearest major forward destination, signs only the small city of Indio, California and "other Desert Cities". [1]

A control city is not always a major city. For instance, Interstate 76 heading westbound out of Philadelphia, Pennsylvania uses Valley Forge, a historic but minor locality where I-76 joins the Pennsylvania Turnpike.

Occasionally, a large city will not be a control city because a larger city is located further down a highway. For example, highway signs in Maryland on Interstate 95 northbound between the Interstate 395 junction in Baltimore and the Mason-Dixon Line at the Delaware border use New York City as their control city, even though I-95 directly passes through the closer Philadelphia, Pennsylvania. Similarly, I-95 north of New York uses New Haven as the control city, as it is more well known than the cities of Stamford or Bridgeport. Another example is in California on US 101 where San Francisco is the control city north of Ventura, even though the highway first passes through the larger, but less famous San Jose. (However, at the time of US 101's construction and signage placement, San Francisco was the larger city.) US 101 in this region is an example of using two control cities: the next intermediary regional destination (in this example, San Jose, Salinas, San Luis Obispo, Santa Barbara and Ventura) as well as the larger and more distant destination (in this example, San Francisco northbound and Los Angeles southbound).