The Cocopah I (often simply called Cocopah) was a stern-wheel paddle steamer and the fifth steamboat to operate on the Colorado River. It was launched in August 1859 and served until 1867.
Construction and Specifications
Built in 1859 in San Francisco for George A. Johnson & Company at a cost of $35,000 (roughly equivalent to over $1 million today), it was the largest steamboat yet placed on the river. Key specifications include:
- Length: 140 feet
- Beam (width): 29 feet
- Draft: Approximately 14.5–19 inches even when fully loaded (sources vary slightly; commonly cited as a mere 19 inches with full cargo)
- Cargo capacity: Up to about 60–100 tons (it could also tow barges carrying additional tonnage)
- Type: Stern-wheel paddle steamer with a powerful engine suited to pushing heavy loads against strong currents
It was specifically designed to replace Johnson’s earlier side-wheeler General Jesup and to handle the Colorado’s difficult conditions—shifting sandbars, snags, shallow water (especially in low-water seasons), and strong currents. The stern-wheel configuration and shallow draft made it far better suited to these conditions than earlier side-wheel vessels.
The boat was disassembled in San Francisco, shipped to the mouth of the Colorado River, transferred to another vessel, and taken upriver to Gridiron Landing in Sonora, Mexico, where it was reassembled and launched in August 1859.
Role on the Colorado River
Operated by George A. Johnson & Company (later associated with the Colorado Steam Navigation Company), the Cocopah I played a central role in the commercial and military development of the lower and middle Colorado River corridor during the late 1850s and 1860s.
It ran routes primarily from the river’s mouth/Gulf of California area (and later the safer Port Isabel Slough) northward. Key destinations included Fort Yuma (about 120 miles upriver), La Paz/Ehrenberg area mining districts, Fort Mohave/Hardyville (roughly 300 miles), and occasionally farther during high water (toward Eldorado Canyon or similar points). Wood yards along the river, often staffed by Cocopah laborers cutting cottonwood and mesquite, supplied fuel.
Captain David C. Robinson (a longtime Johnson employee who had previously commanded the exploratory steamer Explorer far upriver) was its primary early captain.
The vessel transported freight, passengers, mining equipment, provisions, and military supplies. It supported:
- U.S. Army posts (notably Fort Yuma and the newly established Fort Mohave after the 1858–1859 Mohave War)
- Early gold and silver mining booms along the river
- Settlement and commerce in what became Arizona Territory and adjacent areas
One of its early major tasks involved supporting military logistics connected with Fort Mohave (established 1859). Steamers including the Cocopah helped move troops, artillery, and supplies upriver when overland routes proved difficult. Freight rates by steamer were dramatically lower than overland teamster rates, helping open the region economically.
The Cocopah I exemplified the shift to larger, more capable stern-wheelers that made regular commercial navigation practical on the challenging Colorado.
Ultimate Fate
The Cocopah I remained in service until 1867. By then it had seen heavy use; accounts note boiler repairs and eventual condemnation as unseaworthy. Its boiler and engine were removed, and the hull was hauled ashore at Port Isabel, Sonora (the company’s port and shipyard settlement near the river mouth). There it was converted into housing for workmen.
It was replaced by the larger Cocopah II (launched 1867 at Arizona City), which continued in the fleet for more than a decade until railroad competition (especially the Southern Pacific bridge at Yuma) ended the main era of Colorado River steamboating.
The Cocopah I is remembered as a pioneering large stern-wheeler that helped establish reliable steam navigation on the Colorado and supported the military, mining, and settlement expansion of the desert Southwest in the mid-19th century. Primary sources for these details include Richard E. Lingenfelter’s Steamboats on the Colorado River, 1852–1916 and National Park Service historical summaries.