American Sign Language, also known as ASL or Ameslan (old term), is a language in visual-spatial modality. It is dominantly used by culturally Deaf people in the U.S. and speaking-English Canada. ASL is the 3rd (then 4th) most used language in the U.S.
The minister Thomas Hopkins Gallaudet met a little deaf girl, Alice Cogswell, in his neighborhood in Connecticut. Alice's father Dr. Cogswell and Gallaudet were interested in deaf education. There were no deaf schools in the U.S. at that time. Gallaudet traveled to England and then France to learn about deaf education and teaching methods.
Gallaudet was invited to visit the public school for the deaf in Paris. There Gallaudet asked a brilliant young deaf teacher, Laurent Clerc to come to America with him. They founded the first permanent school for the deaf, American Asylum (now the American School for the Deaf) in Hartford, Connecticut in 1817.
The Old French Sign Language (OFSL) that Clerc brought to the U.S. was intermingled with the previous native sign languages. ASL has been evolved since then.
In the 1960s, William Stokoe, a hearing English professor at Gallaudet University (formerly Gallaudet College), observed sign language used by the Gallaudet students. He studied and discovered that it had linguistic features (phonology, morphology, syntax, and all) like any spoken language. He researched and proclaimed that it is a language. His works were published in linguistics journals. Since the 1970s, a number of research and studies have quickly grown.
In the 1980s, credit courses in ASL bloomed in some colleges and universities as well as in high schools across North America.
In the 1990s and onward, cognitive neuroscientist Dr. Laura-Ann Petitto (1954-) is known for her scientific discoveries involving early language acquisition in sign language, pronoun acquisition in language development, manual babbling, and bilingualism. Her studies show that language is amodal, which means that language is independent from modality -- the brain doesn't tell the difference between hands and lips.
Today millions of Deaf people, friends, colleagues, and family members speak ASL on a daily basis. ASL has been popular for second language learning in post-secondary education. There are many ASL courses provided in secondary and post-secondary education, continuing education programs, and private classes in North America.
Related: Old ASL