When young people began going to prom in the late 19th century, it wasn’t yet a dance for high schoolers. Prom, short for “promenade,” was originally an event for college students in the northeast that had its roots in debutante balls. Also known as “coming out” parties, debutante balls introduced young women to “polite society” and its eligible men.

For middle-class white women who might not be able to afford debutante balls, co-ed prom parties for graduating students served a similar function by introducing women to the adult world of manners and etiquette and putting them on display for potential husbands. According to Mic, “Early proms were governed by the same rules and dress codes as debutante balls were: they were racially segregated, for instance, and girls were forbidden to wear masculine clothing.”

In the 1920s, white high schools began to introduce proms to their teenage students. Like the college proms, these were meant to teach students how to behave as respectable men and women along gender and racial lines, and also excluded Black students. By the time the Great Depression hit in the 1930s, the prom had become a big enough deal that some high school principals cancelled their proms so that poorer students wouldn’t be “psychologically wounded.”

But proms really took off in the 1950s, when a post-war boom and new consumer market geared toward teenagers made the celebration a mainstay of the high school year—and one that boys should invite girls to, not vice versa. One 1950s advice book for teenagers lectured that “‘Girls who [try] to usurp the right of boys to choose their own dates will ruin a good dating career,’” according to Ann Anderson in High School Prom.

After Brown vs. Board of Education was decided in 1954, white schools in the south actively worked to undermine the Supreme Court’s ruling that schools couldn’t segregate students by race. In the 1960s and ‘70s, many white schools that had integrated their classrooms began to hold two proms: one for white students and one for Black students. In the famous case of Charleston High School in Mississippi, white parents began organizing invite-only proms for white students in 1970, the year Black students began attending. In response, Black parents organized their own prom for their kids.

Charleston High’s proms received national attention in 1997, when actor Morgan Freeman promised to pay for the school dance if it agreed to hold one integrated prom. The school refused and continued holding racially segregated proms until 2008—a saga detailed in the documentary Prom Night in Mississippi. But Charleston isn’t even the most recent school to desegregate its prom. Students at Wilcox County High School in Abbeville, Georgia, only held their first integrated prom in 2013 (the whites-only prom was scrapped the following year.)

In addition to segregated proms, students have also pushed back against gendered rules about prom attire and policies that prohibit same-sex couples. In 1979, two students became the first acknowledged gay men to attend a high school prom together in the U.S., said the National Gay Task Force. Since then, students have continued to push for LGBTQ-inclusive proms where students can take whomever they want to the dance, and also dress in a way that doesn’t adhere to traditional gender norms.

As schools struggled with racial and LGBTQ inclusion between the 1980s and today, prom became a more prominent subject in the media. A new genre of “teen movies” like Pretty in Pink (1986), She’s All That (1999), and Mean Girls (2004) portrayed prom as a major event for drama and romance. Just like in the movies, students in wealthier parts of the country began to take limos to prom, which were increasingly held at hotels instead of school gyms.

But the biggest change to the American prom in the past few years is something even recent grads might not have heard of: the promposal. This is much more elaborate than simply asking someone, “Will you go to prom with me?” Promposals are usually something that students do if they’re already in a relationship (and suspect the answer to the invite will be “yes”), like sending their significant other a pizza that says “PROM?” or showing off their fire dancing skills.