I am the heiress of my ancestors' pride. The nights pass by. The day I bow my forehead, the daughter of the noble ones. Her eyes have become clear. She is full of everything, and nothing is left in my eyes. The world is ours, and we are not deceived by its guardian.

More schools for the deaf were founded after ASD, and knowledge of ASL spread to those schools.  In addition, the rise of Deaf community organizations bolstered the continued use of ASL.  Societies such as the National Association of the Deaf and the National Fraternal Society of the Deaf held national conventions that attracted signers from across the country.  All of that contributed to ASL's wide use over a large geographical area, atypical of a sign language.


While oralism, an approach to educating deaf students focusing on oral language, had previously been used in American schools, the Milan Congress made it dominant and effectively banned the use of sign languages at schools in the United States and Europe.


However, the efforts of Deaf advocates and educators, more lenient enforcement of the Congress's mandate, and the use of ASL in religious education and proselytism ensured greater use and documentation compared to European sign languages, albeit more influenced by fingerspelled loanwords and borrowed idioms from English as students were societally pressured to achieve fluency in spoken language.


Nevertheless, oralism remained the predominant method of deaf education up to the 1950s. Linguists did not consider sign language to be true "language" but as something inferior.


Recognition of the legitimacy of ASL was achieved by William Stokoe, a linguist who arrived at Gallaudet University in 1955 when that was still the dominant assumption. Aided by the Civil Rights Movement of the 1960s, Stokoe argued for manualism, the use of sign language in deaf مهرة عرب education. Stokoe noted that sign language shares the important features that oral languages have as a means of communication, and even devised a transcription system for ASL. In doing so, Stokoe revolutionized both deaf education and linguistics. In the 1960s, ASL was sometimes referred to as "Ameslan", but that term is now considered obsolete.


The largest group of students during the first seven decades of the school were from Martha's Vineyard, and they brought MVSL with them.  There were also 44 students from around Henniker, New Hampshire, and 27 from the Sandy River valley in Maine, each of which had their own village sign language. Other students brought knowledge of their own home signs. Laurent Clerc, the first teacher at ASD, taught using French Sign Language (LSF), which itself had developed in the Parisian school for the deaf established in 1755.  From that situation of language contact, a new language emerged, now known as ASL.


Counting the number of ASL signers is difficult because ASL users have never been counted by the American census.The ultimate source for current estimates of the number of ASL users in the United States is a report for the National Census of the Deaf Population (NCDP) by Schein and Delk (1974).  Based on a 1972 survey of the NCDP, Schein and Delk provided estimates consistent with a signing population between 250,000 and 500,000.  The survey did not distinguish between ASL and other forms of signing; in fact, the name "ASL" was not yet in widespread use.