Were most of the Hispanos assimilated into the Anglo-American population to the point that most of their descendants nowadays don't bear Spanish surnames and aren't aware of their distant Spanish/Mexican ancestry?
Language:
Well, linguistically speaking, over 95% of them are native English speakers at this point, among the New Mexican Hispanos, there is a still a small minority that still speaks the
New Mexican Spanish dialect, but it's mainly among the elderly population, however due to intermarriages between New Mexican Hispanos & more recent Mexican immigrants, a new dialect of Spanish have been arising called
Renovador, which is a hybrid dialect of both New Mexican & Mexican Spanish.
Among Tejanos, I think they didn't develop their own dialect of Spanish, instead adopting the Mexican Spanish dialect of Northeast Mexico (such as Nuevo Leon), as most of the colonial Mexican settlers were from that part of Mexico, & unlike the New Mexican Hispanos, they weren't isolated from Mexico long enough to develop their own dialect, but also keep in mind, that some Tejanos are fluent in Spanish due to also have recent Mexican immigrant ancestry in addition to having colonial Tejano ancestry, but I would say the vast majority of them are native English speakers at this point, & some have learned Spanish over the recent decades (such as the late Selena or Eva Longoria) due to the massive Mexican immigration & unacceptance from Anglos/Non-Hispanic Whites, & for better economic/social opportunities
There were also some other Colonial Spanish dialects such as the
Sabine River Spanish (among the Sabine River in between Texas & Louisiana),
Isleno Spanish (spoken among the Canary Islander descendents in Louisiana), &
Californio Spanish (spoken among the Californios in California), I couldn't find any videos showing Native speakers of Sabine River Spanish & some sources have pointed out there were only around 100 native speaker in the 1980s (& were most likely elderly people) so likely the dialect is likely extinct at this point, & Isleno Spanish is mostly spoken by Elderly people, just like the New Mexican Spanish dialect, about the Californio Spanish dialect, I was able to find two videos that featured native speakers of the Californio spanish dialect.
Videos about the Californio Spanish dialect.
Here are some videos on the Isleno Spanish dialect.
Video on the New Mexican Spanish dialect.
As you can see, the Native speakers of the New Mexican & Isleno dialects of Spanish are very elderly at this point, as the younger generations are only speaking English, while those three speakers of the Californio Spanish are dead now, the first video was from a TVE special in the early 1990s (& they were already older, especially the guy in the hat), while the other video (featuring Leo Carrillo) was recorded in the 1960s shortly before his death, so I believe that probably the Californio Spanish dialect is extinct at this point, while the New Mexican & Isleno dialects are very close to extinction.
Ethnic ancestry:
Among the
New Mexican Hispanos, I would say that the majority of them are still fully New Mexican Hispano (with a minority also having more recent Mexican immigrant ancestry as well), with some also being mixed with Non-Hispanic White (such as Governor Michelle Lujan, for example), & likely some, if not most of the Spanish/Criollo-looking New Mexican Hispanos are probably at least part Anglo/Non-Hispanic White, however if you see vintage photos of New Mexican Hispanos from the 1800s & early 1900s, you'll see that a lot of them looked very Spanish, but in more recent generations, they have become more Amerindian-admixed by mixing with more Mestizo New Mexicans, as well as full-blooded Native Americans (such as the
Pueblo, Apache, & Navajo), the majority of the
Hispanos of New Mexico identify as
Spanish/Spaniard, with a growing number identifying as
Mexican, & some also identify as both
Mexican &
Spanish/Spaniard.
As for
Tejanos, I think that most of them are still fully Tejano, but I believe quite a significant number might also have recent Mexican immigrant ancestry, as most of the Tejanos live close to the Mexican border, but a smaller number are also mixed with Non-Hispanic White, the Tejanos prefer to identify as Tejano, but when asked of their ethnic ancestry, they usually identify as
Mexican, only a tiny minority of Tejanos identify as Spanish/Spaniard, & it's likely mainly among the Tejanos of San Antonio who have traced ancestry to the Canary Islands.
As for other Hispano populations, the
Islenos of Louisiana, they are actually the most unmixed
Colonial Spaniards in the New World, they didn't really mix with Amerindians unlike the rest of the Spanish Empire, instead they mixed heavily with French Cajuns, & some other Non-Hispanic Whites, meanwhile, the
Californios are heavily mixed with Non-Hispanic White, recent Mexican immigrants, or more recent tribal affiliation or all three at this point, I don't think there are any full-blooded Californios anymore, the
Californios either identify as
Spanish/Spaniard or
Mexican, or both, while the Islenos of Louisiana usually identify as
Spanish/Spaniard, almost all of the time.
So, I would say answering your question,
Californios are the most heavily Anglo admixed Colonial Hispanos, while the New Mexican Hispanos & Tejanos are still full-blooded, while the Islenos of Louisiana are either fully Spanish or heavily mixed with Cajun French.
