Final answer:
Area IV on the map indicates the Mexican Cession, which refers to the territory acquired by the United States from Mexico following the Mexican-American War and the Treaty of Guadalupe Hidalgo in 1848.
Step-by-step explanation:
Area IV on the map indicates the Mexican Cession. The Mexican Cession refers to the territory acquired by the United States from Mexico following the Mexican-American War and the Treaty of Guadalupe Hidalgo in 1848. This territory included present-day states such as California, Nevada, Utah, Arizona, and parts of Colorado, New Mexico, and Wyoming.