Historically speaking, the area now comprising the U.S. had two types of colonial home plans styles: the English colonial typical of the north Atlantic coast, and the Spanish colonial typical of the Gulf coast and the southwest. There has been a great deal written about the English colonial architectural style, but relatively little about the Spanish. The territory in which Spanish colonial architecture dominated extends from the Mexican border northward, including the part of California south of Sonoma County, the whole of New Mexico and Arizona, most of Texas and Florida, and parts of the Gulf states.
The Spanish conquest of America began in 1519 with the defeat of the Aztecs. Soon thereafter missionaries arrived to convert the heathen. By the mid-seventeenth century there were three dozen missions in northern Mexico; and by 1800 missions had been established as far north as Baja California and Arizona. By this time also the viceroys who ruled Mexico were expanding their political hegemony into what is now American California, and settlers were moving in - some of whom became wealthy and built dwellings similar in style to the old country. By the mid-eighteenth century the chain of mission churches, which was the backbone of Spanish civilization in North America and the chief agency of colonization, had been established (reaching San Francisco by 1776, and reaching its northern limit in Sonoma by 1823).
Because of the influence of the structural forms developed by the pueblo Indians before the Spanish arrived, the Spanish style house plans of New Mexico are very different from those which arose in other states. This style may be considered equally Spanish and Indian in character - Spanish in idea, form and plan but Indian in detail and methods of construction. As a result, this architecture has a quaint, primitive interest.
In Texas, the Franciscan style of architecture prevailed. Franciscan missions consisted of the following buildings, laid out for convenience and easy defense: the church, priests' house (usually there were two priests - one in charge of temporal affairs and the other spiritual matters), shops for trades and crafts taught to the Indians, storehouses, kitchen and dining areas, guard rooms for military, hospital, young men's and young women's quarters, school rooms, barns and other agricultural structures, and a village for Indian families. The trades and crafts taught included carpentry, basketry, shoemaking, pottery, fruit growing, stock raising and butchering. Usually Spanish house plans were arranged around an open courtyard flanked by cloister-like arcades, which afforded communication between rooms and buildings. The church was at one side, and often was constructed with an open chapel (three-sided, in order to hasten construction and permit more people to enter). Most of the buildings, including the church, were designed with military purposes in mind and thus tended to be plain and massive. Although as time went on an intricate and elaborate style of ornamentation was often used, still the simple, solid construction as exemplified by the California missions held sway.