When I first saw this pic I thought it was yet another abandoned drive-in, but it turns out that the Ford Drive-in in Dearborn is open nightly with 5 screens! Their website just lists movies, but the Ford Drive-in entry at Cinema Treasures explains:
Opened in 1950, as a single-screener, with a colossal, late Streamline-style screen, the Ford-Wyoming could originally accommodate around 750 cars. It also once advertised a kiddie playground and boat rides for children.
The drive-in was acquired by Wayne Amusements in 1981, and by 1990, and grown to five screens. Another four screens were built during the early-1990’s.
Today, the still-very popular drive-in is the largest in the United States, parking-wise, with space for over 3,000 cars. (The largest drive-in screen-wise is the Thunderbird in Fort Lauderdale, Florida with 13 screens).
The Ford-Wyoming is open year-round, a rarity for drive-ins, and supplies car heaters along with speakers during the winter season.
Screens 6-9 were closed and demolished in May 2010, and in June 2010 it was renamed Ford Drive-In
WaterWinterWonderland has an entry with tons more information and photos of the Ford-Wyoming Drive-in including some nice aerial views.