San Diego has long been well-versed in vice, dating back to when the Stingaree — now the Gaslamp District — was full of saloons, gambling dens, and women for rent.

By 1910, at least 143 hookers worked the Stingaree, and one bordello had 19 prostitutes on duty. Cops generally looked the other way with some notable exceptions, like the time they reportedly nabbed the mayor and police chief in a brothel raid.

Within a few years, however, the brothels began to vanish as prostitutes took to the streets. They remain there today, as we reported in our story earlier this week explaining why El Cajon Boulevard is San Diego’s hotspot for prostitution.

How did downtown lose its ladies of the evening to other parts of the city? Two reasons: high-minded reformers and low-cost automobiles.

The reformers came with the Progressive era, which brought us such things as food and drug regulations, the referendum and the recall and, in San Diego at least, free trash collection.

At the time, just about every city with more than 100,000 people had brothels. “These red-light districts were a fixture of this time and as visible and prevalent as horsedrawn carriages, bustles and large hats. Everybody knew where they were and where to go,” said Karen Abbott, author of “Sin in the Second City: Madams, Ministers, Playboys and the Battle for America’s Soul.”

San Diego’s population was only about 17,700 in 1900, but sailors provided a steady customer base, and brothels lined the streets in the Stingaree district around Third Avenue and I (Island) Street. The neighborhood was home to “bawdy houses” and dance halls dating back to at least the 1880s, as historian Richard Pourade wrote:

A graphic description of one dance hall in the “Stingaree” district was provided by a sleuth hired by The San Diego Union. This particular hall, when he visited it, was crowded with at least 400 persons, many of them “callow youth and balding rakes,” who sat around drinking beer and listening “to the alleged music of an alleged orchestra and feasting their eyes on the alleged charms of stage ‘daisies.'” There was a stage at one end of the long hall and on the other side there was a long row of “private boxes” in the shape of a balcony from which “the gaudy women, scantily dressed, display themselves on the railings … and wave their handkerchiefs at the crowd below.”

By the turn of 20th century, as historian Elizabeth MacPhail put it, “the oldest profession, thanks to the pawers that be, still flourished openly in San Diego.” (No word on whether the typo was on purpose.)

“Every city election that came along heard candidates promising to clean up the Stingaree; but after the election, the subject was dropped,” she wrote.

The Progressives, however, were serious. They didn’t believe in the idea of segregating vice districts to specific parts of town as a kind of “quarantine that would not harm the city as a whole,” Abbott said.

In 1912, a group of prominent citizens called for, as historian Clare V. McKanna, Jr., put it, “the closing of the red light district, the prevention of prostitution in hotels and boarding houses, the dissemination of knowledge on the health problems with venereal disease among prostitutes, and the protection of young people from such vices.”

Some worried about the effects of a crackdown. “The women will only go to infect another city,” warned Mrs. L.K. Lanier of the Shakespeare Club.

That they did. A 1912 newspaper headline read: “138 Are Arrested in Stingaree Raid/136 Promise to Leave City; Two Agree to Reform.”

Newspaper coverage of 1912 prostitution raid in downtown’s Stingaree district.

One of those arrested said: “I would like to be good again, but the world won’t let me. It must keep me as I am.”

San Diego’s prostitutes never left for good, however. Over the first decades of the 20th century, they moved from brothels to hotels, motels and private houses, although there were raids in the Stingaree as late as the 1930s.

The automobile helped: it allowed easy access to both privacy — the backseat is said to have helped spark the 20th century’s sexual revolution — and transportation.

Prostitutes, as author Abbott put it, “could make house calls.” And their local customers in the mid-century, like those traveling on San Diego’s main east-west thoroughfare, could find their way to them more easily.

And so the prostitution business moved to El Cajon Boulevard where, as our story showed this week, it’s never left.