annexation of Texas and the Southwest introduced a Hispanic population that had full citizenship status. About 10,000 Californios lived in the southern part of California, and were numerically overwhelmed by migrants form the East by 1900 that their identity was almost lost. In New Mexico, by contrast, the Mexican population maintained its highly traditionalistic and religious culture, and retained some political power, into the 21st century. The Tejano population of Texas supported the revolution against Mexico in 1836, and gained full citizenship. In practice, however, most were ranch hands with limited political rights under the control of local bosses. Industrial Northeast The industrialization of the Northeast dramatically changed the social structure. New wealth abounded, with the growth of factories, railroads, and banks from the 1830 to the 1920s. Hundreds of small cities sprang up, together with 100 large cities (of 100,000 or more population by 1920). Most had a base in manufacturing. The urban areas came to have a complex class structure, compounded of wealth (the more the better), occupation (with the learned professions at the top), and family status (the older the better). Ethnic-religious groups had their separate social systems (such as German Lutherans and Irish Catholics). The New England Yankee was dominant in business, finance, education, and high society in most Northern cities, but gradually lost control of politics to a working class coalition led dominated by bosses and immigrants, including Irish Catholics. Hundreds of new colleges and academies were founded to support the system, usually with specific religious or ethnic identities. Heterogeneous state universities became important after 1920. Ethnicity and social class The most elaborate and in-depth studies of social class have focused on the working class, especially regarding occupation, immigration, ethnicity, family structure, education, occupational mobility, religious behavior, and neighborhood structure. Before 1970, historians emphasized the success and the painful processes of assimilation into American culture, as studied by Oscar Handlin. In recent decades the internal value systems have been explored, as well as the process of occupational mobility. Most of the studies have been localized (because of the need for the exhaustive use of censuses and local data) so that generalizations have been difficult to make. In recent years European scholars have become interested in the international flows so that there are now studies following people from Europe to America over their lifetimes. Labor historians have moved from a focus on national labor unions to