Throughout the United States there is a mature system of taxicabs. Most U.S. cities have a licensing scheme which restricts the number of taxicab

Taxicab

A taxicab, also taxi or cab, is a type of vehicle for hire with a driver, used by a single passenger or small group of passengers, often for a non-shared ride. A taxicab conveys passengers between locations of their choice...

s allowed.

In New York City a 'medallion' is required in order to legally pick up passengers flagging on the street. Very few other cities have medallions, and most cities never allowed City permits to be traded at will by the public—but in New York City the medallion represents an investment instrument that has soared in value to astronomical heights.