The Atlanta skyline AP Photo/David Goldman Atlanta, Ga.'s underground commercial sex economy is unusually large, with a lucrative market for street prostitution, according to a new study on sex trafficking and sex work in U.S. cities.

Of 7 major cities profiled by The Urban Institute, only Atlanta and Seattle saw their illegal sex trade grow between 2003 and 2007. The study estimated Atlanta's market was $290 million by 2007, compared to just $103 million for Washington, D.C.

Since 2005, Atlanta's pimps have been pulling in an average of $33,000 a week, compared to about $12,000 a week in Dallas and about $11,000 in San Diego.

Here's a breakdown of income for various cities from the report:

Even though more people are posting online prostitution ads these days, the report found Atlanta still has a "very high and extremely profitable" demand for street prostitution. This demand could come from out of town or the suburbs, as Atlanta has major highways running through it, including I-75, I-85, and I-285.

The problem seems to be particularly bad along "densely urban areas" like Fulton Industrial Boulevard, the study found.

"You’ve got your major rappers from Atlanta come down to Fulton Industrial and shoot videos in the neighborhoods, on the streets, with the girls, and with the pimps and then pay $1,000 for the girls to come in and have sex with them," one unnamed law enforcement was quoted in the study as saying.

Not everybody pays as much as "rappers from Atlanta," though. Here's more information from the study on pricing structures for street-level and online prostitution:

The typical pricing structure on the street is $50 to $100 for oral sex and $75 to $150 for “full service.” However, drug-addicted sex workers charge as little as $10 for oral sex and $50 for “full service.” Online, sex workers charge from $60 to $100 for 15 minutes and from $250 to $300 per hour for dates.

One law enforcement officer noted, “The younger the girl, the higher the price—so you could have a girl at 18 that’s going to charge $450 an hour or $350 an hour and that’s kind of funny, as you see them get older into their 30s, unless they have a specialty, you’re going to see them at maybe $150 an hour or something like that.”

In Dallas, by contrast, prostitutes start at roughly $60 for oral sex, even though their pimps don't bring in nearly as much money as Atlanta pimps do. This raises the possibility that Atlanta pimps have more prostitutes working for them so they can make a high weekly wage.