Which explorer claimed the southwest area of present day US for Spain?

The explorer who claimed the southwest area of present-day United States for Spain was Francisco Vázquez de Coronado. In the 1540s, he led an expedition through parts of present-day Arizona, New Mexico, Texas, Oklahoma, and Kansas in search of the fabled Seven Cities of Gold. Although he did not find the riches he sought, his journey significantly contributed to European knowledge of the region. Coronado's exploration laid the groundwork for future Spanish claims and settlements in the area.