USA

The first mixed-sex institute of higher education in the United States was Oberlin College in Oberlin, Ohio, which was established in 1833. Mixed-sex classes were admitted to the preparatory department at Oberlin in 1833 and the college department in 1837. The first four women to receive bachelor's degrees in the United States earned them at Oberlin in 1841. Later, in 1862, the first black woman to receive a bachelor's degree (Mary Jane Patterson) also earned it from Oberlin College. Beginning in 1844, Hillsdale College became the second college to admit mixed-sex classes to four-year degree programs.

The University of Iowa became the first coeducational public or state university in the United States in 1855, and for much of the next century, public universities, and land grant universities in particular, would lead the way in mixed-sex higher education. There were also many private coeducational universities founded in the 19th century, especially west of the Mississippi River. East of the Mississippi, Cornell University admitted its first female student in 1870

Around the same time, single-sex women's colleges were also appearing. According to Irene Harwarth, Mindi Maline, and Elizabeth DeBra: "women's colleges were founded during the mid- and late-19th century in response to a need for advanced education for women at a time when they were not admitted to most institutions of higher education." Notable examples include the prestigious Seven Sisters, of which Vassar College is now coeducational and Radcliffe College has merged with Harvard University. Other notable women's colleges that have become coeducational include Ohio Wesleyan Female College in Ohio, Skidmore College, Wells College, and Sarah Lawrence College in New York state, Goucher College in Maryland, and Connecticut College.

 Primary and secondary schools

Several early primary and secondary schools in the United States were single-sex. One example is Collegiate School, a boys' school operating in New York by 1638 (at the latest).

Nonetheless, mixed-sex education existed at these levels in the U.S. long before it extended to colleges. For example, in 1787, the predecessor to Franklin and Marshall College in Lancaster, Pennsylvania, opened as a mixed-sex secondary school. Its first enrollment class consisted of 78 male and 36 female students. Among the latter was Rebecca Gratz, the first Jewish female college student in the United States.[citation needed] However, the school soon began having financial problems and it reopened as an all-male institution. Westford Academy in Westford, Massachusetts has operated as mixed-sex secondary school since its founding in 1792.

Coed as slang

In American and Canadian colloquial language, coed is also an informal term for a female student attending a formerly all-male college or university (or any university). This usage reflects the historical process by which it was often female pupils who were admitted to schools originally reserved for boys, and thus it was they who were identified with its becoming "coeducational". The word is also often used to describe a situation in which both sexes are integrated in any form (e.g., "The team is co-ed").