KJZZ is a service of Rio Salado College,
and Maricopa Community Colleges

Copyright © 2024 KJZZ/Rio Salado College/MCCCD
Play Live Radio
Next Up:
0:00 0:00
Available On Air Stations

Q&AZ: How did Arizona get its shape?


Through KJZZ's Q&AZ reporting project, a listener asked: How did the state of Arizona gets its shape?

Arizona’s boundary history is shared with its neighbors, particularly the state of New Mexico.

Before Arizona was even part of the United States, it was in the hands of Spain and then Mexico, said Jarrod Riddle, an Arizona historian and owner and operator of Spirit of Arizona Tours.

“All of the political lines that have been drawn in Arizona, they’ve only been about the last 500 years or so,” Riddle said. 

The creation of Arizona’s boundary started back in 1848 when the United States got the New Mexico Territory after the Treaty of Guadalupe Hidalgo that ended the Mexican-American War, according to the Arizona Geographic Alliance.

The northern and part of the western boundary we know today was part of the New Mexico Territory. However, the southern boundary was made by following the Gila River, and part of what is now the southern tip of Nevada was part of the territory.

It was not until 1854, when the U.S. and Mexico finalized the Gadsden Purchase, that the New Mexico Territory and its straight-lined southern boundary were acquired, according to the Arizona Memory Project. The U.S. paid Mexico $10 million for the 29,670 square miles, according to the Office of Arizona Historian.

Discarded Arizona boundary would have included oceanfront property

The idea of oceanfront property today is unrealistic, but at one point, Arizona had lobbied to have part of Baja California so there would be ports, but the Mexican government rejected the proposal, Riddle said.

“If you notice the shape of Arizona, how it starts to kind of stretch horizontally toward the west, and then it kind of curves up a certain amount of degrees,” Riddle said. “The U.S.’ intention was to have that just go straight across. At one point, Arizona was going to have ocean.”

The New Mexico Territory had Arizona’s northern and southern boundary and part of its western boundary. At one point during the American Civil War, there was legislation to divide the territory into north and south horizontally. Had the proposition passed, Arizona would have been the southern half of the New Mexico Territory.

“Their primary motivation was for getting that southern half of the land was they wanted to build their own southern transcontinental railway,” Riddle said.

Carving out final shape

But that didn’t happen. Instead, there was another proposition to divide the territory down the middle vertically. President Abraham Lincoln signed the Arizona Territory bill into law in 1863, giving Arizona its eastern boundary with the New Mexico Territory. 

In 1867, Congress took the land northwest of the Colorado River and gave it to Nevada, according to state records. Arizona might not have Las Vegas, but its shape was complete. There was only one thing Arizona didn’t have — statehood.

It was another 45 years before Arizona became the 48th state, on Feb. 14, 1912, more than a month after New Mexico.

It was in the short span of a long history that Arizona became the shape we have today.

Q&AZ answers more listener questions

Sarah Min Heller is an intern at KJZZ. She is currently a student at Arizona State University’s Walter Cronkite School of Journalism and Mass Communications, and is getting closer to earning a bachelor's degree. She worked at Cronkite News as a digital reporter prior to joining KJZZ.In her spare time, she enjoys listening to different kinds of music, watching old movies and TV shows, and creative writing when she isn't taking care of her family.