Arizona's organization as a United States territory marks a significant moment in its history, occurring as part of a series of territorial adjustments during the Civil War. The act establishing Arizona was largely motivated by the need to secure control over the southwestern territories for the Union. Previously, much of what is now Arizona was part of the New Mexico Territory, but due to the growing demands and geopolitical concerns amid the Civil War, it became crucial to create a separate entity for administration and control.

President Abraham Lincoln signed the Arizona Organic Act into law on February 24, 1863, after rigorous lobbying by various local factions who had sought greater self-governance and recognition. The legislation provided for a territorial government that included a legislative assembly, various administrative roles, and a judicial system. The first governor, John N. Goodwin, was appointed soon after and faced numerous challenges, including establishing infrastructure and addressing relations with both Native American tribes and settlers who were arriving in the territory.

The organization of Arizona as a territory was not just a local development; it was part of a larger strategy to promote westward expansion and settlement in line with the Manifest Destiny ideology. This led to increased migration into the area, bringing settlers, miners, and ranchers who were drawn to the region's resources. The introduction of governance was also crucial for law and order as communities began to build around economic opportunities, setting the stage for future statehood.