Blocked to the west by the Santa Cruz River and the Tucson Mountains, the city simply followed the path of least resistance.

“It’s not surprising that it would go north and then out east and south,” said Warnock, a professor emeritus of English at the University of Arizona whose new history book, “Tucson: A Drama in Time,” is set for release in October. “There’s just a whole lot of space out there to be taken, isn’t there.”

Annexing the ‘regions of the unknown’

What is surprising, even for an Old Pueblo native like him, is how far the city’s midpoint has traveled. Warnock knew it had moved and in what general direction; he had no idea it had made it all the way to the Air Force base.

“I think a lot of people would be very surprised that that’s the geographic center of the town,” he said.

Geographer Laura Sharp works as a GIS data analyst for the city, a job that requires her to “look at maps of Tucson all day.”

She said the average resident can be forgiven for not knowing exactly where the city limits are, let alone some obscure center point. The boundaries are jig-sawed and confusing, and they seem to change every year. “We have to redo our maps every time an annexation happens,” Sharp said.