Mex-Ams are tied to their group almost as much as blacks: The General Social Survey asked a large sample of Americans if their ethnic group was important to who they are. Here is the percent of each group that answered "very important":
American Indian 41.5
Mex-Ams are almost as ethnocentric as blacks! And they totally outdo American Indians and Jews. Hundreds of years in America hasn't fully assimilated blacks and Indians: how long will it take Mexicans who receive fresh blood from the Old Country every day, and when they do assimilate, it's often toward black ghetto norms?