Atlantic City, New Jersey is a city in Atlantic County, New Jersey and a nationally renowned resort city for (gambling, bookmaking, drinking, prostitution, strip clubs, clubbing). The old days, it was also known for organized crime, bookmaking, bootlegging, brothels, illegal gambling, speakeasies, police corruption, political corruption, prostitution.
Baltimore, Maryland, United States, The Block (prostitution, drugs, strip clubs, organized crime)
Lynn, Massachusetts, United States (gambling, prostitution, drinking, drugs, gangs, violence, corruption, brothels, organized crime)
Las Vegas, Nevada, United States (gambling, bookmaking, easy marriage, easy divorce, sex shows, strip clubs, cabarets, prostitution, (However, prostitution is illegal in Las Vegas and Clark County), clubbing, 24-hour liquor sales (as in all of Nevada); quote: "What happens in Vegas, stays in Vegas."). In former days it was known also for organized crime and corruption.
Los Angeles and neighboring Hollywood (film, television, modeling, music, (i.e. glam metal, gangsta rap), paparazzi, plastic surgery, porn industry, publishing industries, sports, tabloids, air pollution, bank robberies, car chases, clubs, drugs, homeless people, gangs, notorious slums in the poorer areas of L.A., (major glamorous destination for many teen runaways).
New York City (films, music, modeling, tabloids, television, paparazzi, formerly porn industry (Times Square), many teenage runaways, organized crime, BDSM clubs, street performers, gangsta rap.
Reno, Nevada (gambling, drinking, strip clubs, clubbing, easy marriage, easy divorce, prostitution, (However, prostitution is illegal in Reno and Washoe County), 24-hour liquor sales, as in all of Nevada.
Tijuana, Mexico (Organized crime, gangs, drug trafficking, clubbing, drinking, police corruption, political corruption, prostitution)
Former Sin Cities:
New York City in the mid to late 19th Century (prostitution, brothels, illegal gambling, notorious slums, pickpocketing, police corruption, political corruption, drugs, gangs, organized crime), Times Square from the mid-1960s until circa 1990 (prostitution, pornography, go-go bars, sex shops, sex shows, squeegee men, strip clubs, clubbing, drugs, organized crime)
New Orleans from 1897 through 1917, Storyville district (prostitution, brothels, gambling, and speakeasies)
Chicago in the 1920s to 1930s (prostitution, bootlegging, cabarets, speakeasies, illegal gambling, bank robberies, police corruption, organized crime, and gang activity)
Galveston, Texas in the 1920s to 1957 (prostitution, organized crime, gambling, speakeasies, drinking, political corruption)
Montreal, which earned a reputation for vice through American tourists fleeing the prohibition laws.
In 1955, Terre Haute, IN was labeled Sin City by the monthly magazine Stag. (reputation for being "wide open", with gambling and a well-developed "red light district").
In the 1980-1990s Michigan City, IN was considered Sin City, with the proliferation of massage parlors
As you can see, a number of places have claimed that title, whether deservedly or not.