a. New Mexico
Explanation:
During the American Civil War, Confederate troops from Texas initially occupied southern New Mexico. Union troops recaptured the territory early in 1862. Kit Carson collaborated in organizing the First Volunteer Group of New Mexico, which was commanded by himself. This group faced Apaches, Navajos and Comanches, in territory and Texas, as well as participated in the Battle of Valverde against Confederate troops. During the war, the Territory of Arizona was created, in 1863, through the western region of the Territory of New Mexico. With this, New Mexico has acquired its present current borders. New Mexico was the scene of the decisive Battle of Glorieta Pass, where Confederate troops were forced to halt a march to California, retreating to Texas, having been defeated by Union troops as well as Colorado volunteers (The Pikes Peakers) and of New Mexico.
The railroad was responsible for the prosperity of the cattle industry of the 1880s, and for the development of cities that depended on this industry. Cattle breeding was not fixed then, with cattle breeders feeding their animals where they wished, leading to confrontation between several ranchers as well as local authorities in the Lincoln County War. The reign of the cattle industry would lose its strength throughout the 1880s as sheep herders came to surround their holdings with fences, preventing livestock keepers from using the pasture of these properties as food for their animals. This further increased the friction for land tenure in the region, primarily among the former Spanish inhabitants, cattle farmers, and new ranchers, primarily sheep farmers. Despite conflicts, livestock remains a source of New Mexico's primary income to the present day.