Mostly towns and cities are used as control cities. Other than major towns in a country or region, towns close to major intersections or the end of a particular route are often selected as control city. However, all sorts of other potential destinations can be selected as control city, such as states and regions, frequently visited objects, and names of prominent intersecting roads. Narrow-passes carrying a lot of traffic often also take the role of control city. Examples would be major bridges (the Golden Gate Bridge is a control city within San Francisco), tunnels (e.g. the Holland Tunnel in New York City), or mountain passes (e.g. the Gotthard Pass featuring prominently on signs in Switzerland). In border areas, the border itself regularly features as a control city, e.g. the U.S.-Mexico border for Interstate 5 southbound.
