How Did Arizona Get Its Distinctive Shape?

If you look at America's east coast compared to it's western one, you'll notice a different in the shapes of states. The east coast is cluttered with smaller states, all with their own unique shape and size, while the west tends to be full of larger squares placed in a semi-grid.

With that being said, Arizona has a very distinctive shape, so where did that come from?

Arizona's Early Days

The story of Arizona's shape begins with the end of the Mexican-American War in 1948. With the end of the war, America bought land in what would become California, Nevada, Utah, New Mexico, and Arizona for around $18 Million. The treaty that conceded this land labelled the Gila River as the border between the Arizona Territory and Mexico.

The next step was creating the New Mexico Territory during the Compromise of 1850, which laid a straight line at 37 degrees north, marking the northern border for Arizona, New Mexico, and Oklahoma. This border has remained the same into the modern day.

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The Western and Eastern Borders

Much like the southern border of the state, the western was based on an easily identifiable natural phenomenon during the Compromise of 1850. This time: the Colorado River. Unfortunately for the surveyors, the Colorado is a wild, raging river, leading to a slightly changing western border over time.

As time moved on, the U.S. needed more land for the Transcontinental railroad, and thus, bought 29,670 square miles of land in the 1853 Gadsden Purchase, which created the slightly slanted southern border we know today.

Lastly, the Arizona and New Mexico territories were split in 1862, with a straight line down at 109 degrees west longitude. Unfortunately, their work wasn't entirely over, as Congress approved a land purchase from Arizona to Nevada, giving them that missing chunk of land in the northwest border of our state.

[Arizona State University]