The decades after the Civil War saw the rise of the opera house as a venue to attract more fashionable people than those who would attend the traditional theatre. While a theatre could be anything from a barn to a third-floor hall above commercial space, the opera house was specifically built for respectable entertainments. The seating for up to 2,000 people in different sections at various price scales created a kind of social segregation. Often there was a separate box office and side entrance for the cheap gallery seats above the more fashionable balconies. Early opera houses had flat auditorium floors (so that the facility could also be rented for balls) and raked stages. By 1900, most opera houses were built with raked auditorium floors (allowing some visibility above the large hats worn by women) and flat-floor stages.
The opera houses built in towns across the nation tended to devote more space to amenities for the audience—lobbies, refreshment rooms, ladies' parlors, smoking rooms—than did those in New York where square footage was more costly. Each decade brought refinements in ventilation, lighting, fire-prevention devices (sprinklers or "inundators," asbestos curtain, additional exits), actor dressing rooms (eventually with fixed washstands), and scenery and equipment. Few theatres, either in New York or elsewhere, contained their own scene shops; exceptions were Booth's Theatre (1869-1883) and Daniel Frohman's Lyceum Theatre. A number of innovations may be credited to Steele MacKaye at his Madison Square Theatre, which he remodeled in 1879. Leading theatre architects and firms during the modernist period included John Eberson, Thomas Lamb, J. B. McElfatrick and Sons, Herbert J. Krapp, and Henry B. Herts. Opera houses continued to be built outside New York until the 1890s, but then yielded place to somewhat more intimate theatres in the 1900s and 1910s. New York saw many new theatres constructed throughout the 1920s.
The Historical Dictionary of the American Theater. James Fisher.