LOS ANGELES — Drive-in movie theaters that scraped by during the surge in modern multiplexes are edging closer to extinction as Hollywood phases out the 35-millimeter reels they need to show films.

Most of the remaining 368 US drive-ins, down from more than 4,000 in 1958, must decide whether to pay as much as $70,000 to install digital projectors for their large outdoor screens. About 10 percent have, and the United Drive-In Theatre Owners Association anticipates studios will move to electronic delivery only as soon as the end of next year.