When Paramount decided to release the Bob Hope and Bing Crosby comedy Road to Rio in theaters on December 25, 1947, studio executives were slightly concerned. Would moviegoers consider the premiere of a film on Christmas Day to be in poor taste? Would it be offensive to some?

They shouldn’t have worried. The film was a hit, making an impressive $4.5 million, and Hollywood has made Christmas Day (or near-Christmas Day) releases a major part of their financial strategy ever since. The reason? While Christmas is a sacrosanct holiday for many, the closing of businesses creates a vacuum. Few stores are open and diversions are hard to come by, making a trip to the movies one of the only ways families can congregate somewhere other than home during a holiday break. Some theaters report business picks up after 3 p.m. or 4 p.m. in the afternoons, when presents have been unwrapped and people with free time are in search of something to do.

Because of time off from work and school, movies also have a chance to achieve “legs,” or the ability to stretch their success over a longer period. While big-budget films are often deemed a success or failure based largely on their opening weekend box office tallies, a smaller film, like 2007’s P.S. I Love You, can open small and still come out ahead. That particular film made just $6.5 million during its opening weekend, but wound up with $53.7 million through January.

This year, several films will debut on December 25, including the fact-based docudrama Just Mercy, the Will Smith animated comedy Spies in Disguise, the World War I drama 1917, and Greta Gerwig's adaptation of Little Women. If past box office trends hold, it could be a very profitable season for studios. Of the five biggest box office hits of all time—1997’s Titanic, 2009’s Avatar, 2015’s Star Wars: The Force Awakens, 2018’s Avengers: Infinity War, and 2019’s Avengers: Endgame—all but the Avengers films were late-season holiday releases.

While there’s lots of family fare, studios also look to the season to highlight movies that might be in awards contention. From 1986 to 2005, half of all the Best Picture winners at the Academy Awards were released on or after December 15. When the Oscars were moved up a month from March to February, studios moved award hopefuls back. Now, prestige pictures arrive in theaters in October and November, too.

Of course, whether a movie can enjoy a financial windfall during Christmas depends a lot on what part of the world you’re in. While a Christmas run works in America, China tends to fill theaters during the Chinese New Year in late January or February. The French line up over Labor Day weekend. Russia prefers New Year’s Day. For the Japanese, the April and early May Golden Week holiday is a prime theater window. But in all territories, the motive is largely the same: People want something to do with—or a way to briefly get away from—family.