Core signing populations are found in Mexico City, Guadalajara and Monterrey, with a number of smaller cities containing signing communities. Some regional variation is found. Variation is high between age group and people of completely different religious backgrounds.
LSM is quite distinct from Spanish, with completely different verb inflections, different discourse structure and preferences for word order, and little use of the verb to be. However, there is extensive use of initialised signs with one study finding 37% of a 100-word list are initialised, compared to 14% for American Sign Language. The same authors suggest that the Deaf community's comprehension of the Spanish language is very low. The term "Signed Spanish” refers to signing that uses LSM signs in a Spanish word order, with some representations of Spanish morphology. There is a group of suffixes that signed Spanish uses in a way similar to that of signed English, e.g. signed symbols for -dor and -ción. Articles and pronouns are fingerspelled. Signed Spanish is often used by interpreters and during public reading or song-leading. Signed Spanish is also used by some hard of hearing and late deafened people.
LSM is widely believed by the deaf community to have derived from Old French Sign Language, which combined with pre-existing local sign languages and home sign systems when deaf schools were first established in 1869. However, it is mutually unintelligible with American Sign Language, which emerged from OFSL 50 years earlier in the US, although the American manual alphabet is almost identical to the Mexican one. Spanish Sign Language used in Spain is different from Mexican Sign Language, though LSM may have been influenced by it.
Status
In 2005, Mexican Sign Language was officially declared a "national language", along with Spanish and indigenous languages, to be used in the national education system for the deaf. Before 2005, the major educational philosophy in the country focused on oralism and with few schools that conducted classes in LSM. A 5-minute signed segment of a nightly television news program was broadcast in Signed Spanish in the mid 1980s, then again in the early 1990s, discontinued in 1992, and resumed as a 2-minute summary of headlines in 1997.