In 1821, new mexico was a territory controlled by:

mexico

native americans

united states

spain

The answer is Mexico, I know for a solid FACT it's mexico

The correct answer is: Mexico, due to its independence from Spain in 1821.

Santa Fe of New Mexico, or New Mexico, was a province of Spain and later on of Mexico that existed from the end of the 16th century up to mid-19th century. The province was founded in 1598 by Juan de Oñate during one of his expeditions. Oñate established a settlement near Pueblo of San Juan; as time passed by, Oñate hoped that this province will become a separate Viceroyalty from Spain, but he did nor succeeded. The Spanish were expelled from the territory after the Pueblos Revolt of 1680, but in 1692 Spanish defeated the Mexicans and came back in the bloody reoccupation of Santa Fe.

This province maintain under the Spanish control until the Declaration of Independence of Mexico in 1821; under the Federal Constitution of the United States of Mexico in 1824 it became the New Mexico Territory under the federal administration.