When I was a youngster growing up in the 1960s and 70s in Pittsburgh, on Liberty Ave. and Smithfield St. downtown in the Golden Triangle, along with the massage parlors, dirty book stores, and adult theaters, there were barely dressed sex workers plying their trade right out in the open. It was seedy and dirty, and the prostitutes were being victimized. Of course most of it was run by the Mafia or Camorra crime gangs. In DC on 14th St. NW blocks from the White House was an open air sex supermarket into the 1990s, and there was a sex neighborhood near the FBI building which I believe has been gobbled up by Chinatown. NYC's Times Square in the 1970s was unbelievable. ANYTHING someone looking for sex wanted was available for a price. Smartphones have made street prostitution disappear, just as video made the adult theaters vanish, and the internet got rid of the adult video and book stores. Apparently almost every problem has a technological solution. It's a hell of a lot easier than getting people to change, because they don't. Ask a cam girl.