El Centro. The center of what?

Heymatt:

What exactly is El Centro the center of? Hmmmmm?

-- N. Everyman, Ubiquity

El Centro from the beginning was a city with a purpose. W.F. Holt and C.A. Barker bought the land for the town in 1905, built a city center of arcaded brick buildings, then threw open the doors and waited for people and businesses to move in. They knew the Imperial Valley would secede from San Diego County, and they wanted their town to be the county seat when it happened. Holt first named the town Cabarker, after his partner. No surprise, everybody else hated that name. They decided El Centro would be more appropriate for the county seat. The people of the valley voted themselves a separate county in 1907, and El Centro was voted its political center.