"Serial Mom," the John Waters film that opened last week, brings to three the number of made-in-Baltimore films showing here simultaneously. The other two, "Guarding Tess" and "Major League II," however, aren't quite the genuine article. Indeed, "Major League II" features Oriole Park at Camden Yards disguised as a stadium in Cleveland, for heaven's sake! By contrast, "Serial Mom" was filmed in Towson, which appears as Towson in the movie. And with the exception of a few actors, it is a thoroughly Baltimore production.

That has been Mr. Waters' gift to his hometown. By refusing to leave the city, by using Baltimore people and places in all aspects of his movie-making, he has encouraged the development of a movie-making culture, complete with local actors and movie craftsmen and women. That culture, in turn, has encouraged other movie-makers to choose Baltimore.

We have no idea if "Serial Mom" will please the critics or make money, but we do know that John Waters has put Baltimore on the film-making map -- and helped pour millions of dollars into his hometown economy.