The Colorado II was a stern-wheel paddle steamer (sternwheeler) that operated on the Colorado River from 1862 until it was dismantled in 1882. It was the second vessel of that name and the fifth steamboat overall on the lower Colorado River. It played a key role in freight and passenger transport supporting military posts, mining, and settlement in the desert Southwest during the peak of river steamboating.

Background and Construction
Steamboat service on the Colorado River began in the early 1850s to supply Fort Yuma (near present-day Yuma, Arizona) and other points upriver, as overland transport across the desert was difficult and expensive. George A. Johnson & Company dominated the trade. The original Colorado (often called Colorado I), launched in late 1855, was a 120-foot sternwheeler that could carry about 60–70 tons on a shallow draft of under two feet. It used an 80-horsepower engine and was captained at times by Isaac Polhamus (later known as the “Dean of the Colorado River”).
By 1862 the original Colorado was worn out. Its hull was dismantled in April 1862 at Arizona City (Yuma). The engine and boiler were removed and reused. Shipbuilder John G. North (a well-known California steamboat builder) constructed a new, larger hull in San Francisco. The parts were shipped to the Colorado River and assembled/launched at Arizona City under the guns of Fort Yuma, due to fears of Confederate raiders during the Civil War. The new vessel—Colorado II—entered service around December 1862 (some sources note May or later in the year for full operations).
Specifications
- Type: Stern-wheel paddle steamer (sternwheeler)
- Tonnage: 179 tons
- Length: 145 feet
- Beam (width): 29 feet
- Draft: Approximately 16 inches (very shallow, suited to the river’s sandbars and variable water levels)
- Engine: 80 hp steam engine reused from Colorado I
- Cargo capacity: Around 70 tons (some accounts note higher freight capacity in practice; one source cites capacity for 179 tons of freight, aligning with displacement)
- Builder: John G. North (hull); machinery from the prior vessel
- Owners: George A. Johnson & Company, later the Colorado Steam Navigation Company (C.S.N.Co., reorganized 1869)
These shallow-draft design features were essential for navigating the lower Colorado’s shifting channels, sandbars, and seasonal low water.
Role on the Colorado River
Colorado II operated primarily on the lower Colorado River, from the river mouth/delta area (near Port Isabel, Sonora, Mexico, on the Gulf of California) northward past Arizona City/Yuma, to landings serving mining districts, military posts (including Fort Mohave), and settlements in present-day Arizona, California, and Nevada. It carried freight (supplies, mining machinery, ore, wool, agricultural goods), passengers, and often towed barges to increase capacity.
It was part of Johnson’s fleet that held a near-monopoly after absorbing rivals in the 1860s. Key captains included Stephen Thorne. The vessel worked alongside others such as the Cocopah (I and later II), Mohave, Nina Tilden, and barges. Woodyards (often staffed by local Cocopah people) supplied fuel along the route. Trips supported the growth of mining (e.g., in areas like Eldorado Canyon) and military logistics. By the late 1860s–1870s the company (reorganized as C.S.N.Co.) ran multiple steamers and handled thousands of tons of freight and hundreds of passengers annually. Colorado II is documented in period photos, including at Fort Yuma landings and in a tidal dry dock at Port Isabel.
Competition from rival lines (e.g., in the mid-1860s) was short-lived. The arrival of the Southern Pacific Railroad at Yuma in 1877 (with a bridge soon after) sharply reduced the need for long-haul river transport, as rail took over east-west traffic. The steamboat company was sold to Southern Pacific interests. Remaining boats, including Colorado II, continued for a time on residual upper-river and local service.
Ultimate Fate
Colorado II remained in service until 1882, when it was dismantled (sources consistently list 1882; some note August). This was typical for aging Colorado River steamboats once machinery wore out or traffic declined—hulls were often broken up, and usable parts reused or the vessels beached. It outlasted several contemporaries (e.g., Cocopah II was dismantled around 1881). The broader steamboat era on the lower Colorado effectively ended with the construction of Laguna Dam (completed around 1909), which blocked navigation, though limited operations continued a few years longer with smaller vessels.
Colorado II exemplifies the practical, shallow-draft sternwheelers that opened the desert Southwest to reliable waterborne commerce for roughly three decades before railroads and dams rendered them obsolete. Primary details come from historical compilations of Colorado River steamboats, including Wikipedia summaries drawing on period accounts and works such as those referencing MacMullen’s Paddle-Wheel Days in California.