THE WASHINGTON National Opera's live simulcast on the Mall of a full-length opera might have seemed an eccentric idea. Opera buffs, a skeptic might have guessed, want to be inside the opera house, not out on a blanket; and those who don't watch opera, well, don't watch opera. But that skeptic would have been wrong. This weekend, the opera's free simulcast of George Gershwin's masterpiece "Porgy and Bess" was a success: About 13,000 people showed up to watch. That's more than six times the number of people who can fit in the Kennedy Center's Opera House. The unseasonably warm weather surely helped. But opera on the Mall seems like an idea with a surprisingly big constituency.

True, "Porgy" isn't a typical opera. It's in English, for one thing, and its quintessentially American music, which draws as extensively on African American musical styles as on operatic conventions, is well known to many people for whom most opera is remote. The opera also has historical connections with Washington. The original Porgy was famed D.C. baritone Todd Duncan, who taught at Howard University and lived here until his death in 1998. The original cast's refusal to play before a segregated audience at the National Theatre in 1936 prompted the first integrated performances there. Placido Domingo, the opera's general director, was right when he declared that "Porgy" was "made for the Mall."

In light of the simulcast's success, we wonder how many other operas were also made for the Mall. The cost of the simulcast -- in this case, $300,000, all donated by members of the opera's board and Mr. Domingo -- is not exorbitant. The experiment bears repetition and support.