The California Gold Rush of 1848-49 sent thousands of prospectors west, and many of them continued looking after the major deposits played out. The Gila River valley was one of the areas they searched, and in 1858, they found what they were looking for. Gold deposits along the Gila River approximately nineteen miles above its confluence with the Colorado drew a rapid influx of prospectors and the merchants, saloon keepers, and speculators who followed wherever gold was found.

Gila City emerged from that influx. By early accounts, it was a functioning community with the standard infrastructure of a frontier boom: buildings of whatever materials were available, a resident population engaged in mining, and a supporting economy of commerce and services. The daily take for a working miner — twenty to one hundred and twenty-five dollars — was substantial by the standards of the time. The discovery of a twenty-two-ounce nugget circulated as a story of what was possible.

The geography of Gila City's supply chain was unusual. The Colorado and Gila Rivers, before they were dammed, were navigable by shallow-draft steamboats, and the settlements along them received supplies by water. In 1859, the schooner Arno — carrying parts destined to build a steamboat — sank in the river near Gila City during a tidal bore. The incident illustrated both the logistical complexity of supplying a desert gold camp and the unpredictable character of desert rivers, which could run shallow and placid one day and surge with flood force the next.

The tidal bore that sank the Arno was a natural phenomenon of the lower Colorado and Gila system — surges of water from the tidal influence of the Gulf of California, propagating up the river channel with surprising force. It was one of the many hazards of operating in a desert environment that was less tame than it appeared.

The winter of 1861-62 brought exceptional rainfall to the Southwest. The Colorado River, fed by snowmelt and sustained precipitation across a vast drainage basin, rose to levels that had not been seen in recorded history. The Great Flood of 1862 was catastrophic across the region — it destroyed Jaeger City at the Yuma Crossing on the same surge that took Gila City.

Gila City was not designed to withstand a major flood. Like most frontier settlements built near desert rivers, it occupied flat ground near the water — convenient for access but vulnerable to inundation. The flood covered the site completely. The buildings, the mine workings, the accumulated property of several years of activity were swept away or buried under silt.

The community did not rebuild. The gold that had attracted people in 1858 was insufficient reason to reconstruct what the flood had taken, particularly when the surface deposits were by that point substantially worked out. The post office closed on July 14, 1863, which is the administrative date of Gila City's formal end, though the practical end came with the water.

Ghost towns usually leave something. Gila City left nothing that can be identified on the current landscape. The combination of the 1862 flood, subsequent river course changes, agricultural development, and more than 160 years of natural process has eliminated any surface evidence of where the town stood. The site is known from historical records and approximate geographic description — nineteen miles above the Colorado confluence — but locating it precisely on the current ground is speculative.

The Gila River today is a diminished version of the river that flooded in 1862. Dams and diversions have captured most of its flow, and the riverbed is often dry for substantial stretches. The same water management that makes the Yuma area agriculturally productive has eliminated the flood regime that built — and destroyed — the river communities of the frontier era.