USS Missouri was a sidewheel steam frigate of the United States Navy. Alongside USS Mississippi, she was one of the first steam warships of the Navy. She was ordered by Congress in an attempt to force the fleet to modernize and embrace steam engines. Commissioned in 1842, she carried 10 guns, was among the fleet's largest ships and featured barque-rigged sails. Her introduction helped legitimize the role of engineers in the fleet; she was later involved in a scandal that ousted the first engineer-in-chief of the US Navy.

In her first year, she made trial runs along the US East Coast to demonstrate her engines, followed by a deployment to the Gulf of Mexico. In 1843, she made the US Navy's first steam-powered Atlantic crossing, bound for Egypt. While anchored off Gibraltar, spilled turpentine ignited and the resulting fire spread across the ship overnight. An international team attempted to fight the fire, but her captain judged the effort futile and ordered the ship to be abandoned. After the crew evacuated, the ship was destroyed the next morning when her magazine detonated.

By the 1830s, the steam engine began to eclipse sails as the primary propulsion of warships. The US Navy failed to initially embrace the new technology, as conservative senior officers opposed a radical change to the status quo. An additional opponent to steam power was James Paulding, the Secretary of the Navy, who vowed to never "see our grand old ships supplanted by these new and ugly sea-monsters" in reference to steam-powered warships. The Board of Navy Commissioners–an advisory group that executed naval policy–likewise opposed change, and the Navy technologically stalled. By 1839, both the French and Royal navies had at least 15 steam warships in service, far outpacing the Americans. The only steam vessels operated by the Navy that year were the tugboat Engineer and the floating artillery battery Fulton. The technological gap with the European powers led to a public demand for naval modernization. In response, Congress ordered the construction of three "sea steamers" for the Navy that year.

To fulfill the order from Congress, the Navy assembled two boards to develop the new ships. The first group was composed of commodores who outlined the capabilities they would like in the vessels. The second board was made up of engineers and constructors who analyzed the officers' request and developed specific instructions required to build the vessels.

The resulting specifications stated that the new vessels would be dual-powered ocean-going steamships equipped with 10 guns, provisions to supply a crew of 200 for 2 months, and enough coal to power an engine that could develop 9 knots (17 km/h; 10 mph) for 20 days. In addition, the ships also had to have sails to allow them to operate without engine power. The final design was by Joshua Humphreys, Samuel Hartt, and John Lenthall, and featured an overall length of 229 feet (70 m), a beam of 40 feet (12 m), mean draft of 19 feet (5.8 m), a mean draft displacement of 3,220 long tons (3,272 t), and a barque rig with 19,000 square feet (1,800 m²) of sail. After the two boards met, they agreed to only build two steamships, down from the three initially ordered from Congress.

Due to the position of the engine and funnel, the three masts were located in unconventional locations on the main deck. Combined with the funnel preventing the use of mainsails, the design was slow while under sail. The ships were the longest in the Navy, even in comparison to the 120-gun USS Pennsylvania. To prevent hogging (longitudinal bending), the ships were the first American vessels fitted with iron straps to strengthen the hull. The straps were diagonal to the keel and ran to the main deck. The large size was required to have enough space for the engines, coal stores, and provisions while retaining an economical ratio between each dimension.

Armament consisted of four Paixhans 8-inch (20 cm) guns on each broadside that fired 68-pound (31 kg) shells and two bow-mounted Paixhans 10-inch (25 cm) guns that shot 120-pound (54 kg) rounds. The two bow guns were mounted on pivots and had a 146° arc of fire; all ten guns were kept on the main deck. The hulls were made of live oak grown in and around the Atakapa District. Below the gun deck was the berth deck, which housed berthing for the seamen. In the stern were the officers' quarters. Forward of the officers' quarters was the engine, located amidships, which was flanked by a 93-foot (28 m) long coal bunker on either side. The two bunkers could carry 800 tons of coal for 20 days of steaming. In front of the engines were the enlisted quarters which ran to the bow. Below the berth deck was the tween deck, itself above the hold. The hold was subdivided into five compartments by four watertight bulkheads. While otherwise similar, Missouri's interior was better furnished compared to that of her sister ship USS Mississippi. The final design had space to store enough provisions to support a complement of 226 sailors and officers for four months.

The main difference between the ships was the engines, as the Navy wanted to investigate different designs. Missouri was fitted with inclined engines, which were popular with American paddle steamers. Mississippi received side-lever engines, commonly used by trans-Atlantic steamships and the Royal Navy. Missouri was equipped with four double-return copper boilers that provided steam to two inclined direct-acting engines with a 10-foot (3.0 m) stroke and a 62-inch (160 cm) bore. The engines turned two 28-foot (8.5 m) tall, 11-foot (3.4 m) wide paddle wheels that developed 517 indicated horsepower (386 kilowatts) and an average speed of 7–10 knots (13–19 km/h; 8.1–11.5 mph). There were 21 paddles on each wheel; every paddle had a length of 6 feet (1.8 m) and a width of 3 feet (0.91 m).