History: The New York City Subway, United States

Since 1987, MTA has sponsored the "Music Under New York" (MUNY) program in which street musicians enter a competitive contest to be assigned to the preferred high traffic locations. Each year, applications are reviewed and approximately 70 eligible performers are selected and contacted to participate in live auditions held for one day.
At present, more than 100 soloists and groups participate in MUNY providing over 150 weekly performances at 25 locations throughout the transit system. For example, Mr. M. Salieu Suso, a kora player from The Gambia, plays at Union Square.
In addition, any musician/entertainer may perform in subway mezzanines and platforms. On platforms, there may be no amplifications as this is part of MTA policies:
“The New York City Transit (NYCT) is a subdivision of the Metropolitan Transportation Authority (MTA) that operates the city's subways and buses. The NYCT authorizes these types of free expression in subway stations: "Public speaking; distribution of written materials; solicitation for charitable, religious or political causes; and artist performances, including the acceptance of donations.”