Toyota, as of 2024 the second-largest automobile manufacturer in the world, built a $400 million engine plant on a 230-acre site in Buffalo, Putnam County, in 1997. The plant produces engines and automatic transmissions for the Japanese company's North American automobile assembly plants.

In December 1998, the Buffalo plant produced its first four-cylinder engine, with a capacity to produce 300,000 a year. By 1999, the plant had manufactured its first V-6 engine, and two years later, had started building automatic transmissions. In 2005, plant workers built four-cylinder engines for Toyota's Corolla and Matrix models, and V-6 engines for the Sienna and Lexus. Additionally, automatic transmissions were manufactured for the Camry, Solara, Lexus, and Sienna.

The state offered Toyota several incentives to locate the plant in West Virginia, including $15 million in tax credits over 13 years, improvements to State Route 62, job training grants of $1,000 per employee, $2 million for site preparation and start-up expenses, exemption from property taxes on plant equipment for 10 years, and a $50,000 grant for a Saturday school for children of Japanese workers who moved to Putnam County to set up the plant.

Since the plant's opening, Toyota has expanded its West Virginia facility several times. At full capacity, Toyota West Virginia can produce 540,000 engines and 360,000 automatic transmissions per year. With new investments, Toyota expects to produce more than 70,000 engines per year. Its $1.8 billion plant covers nearly two million square foot and employs about 2,400 people, most of whom live in West Virginia. In 2023, Toyota was the ninth largest private employer in West Virginia. About 10 Toyota employees from Japan work there at any time. The Japanese workers usually take a three-year assignment and then return home.

In November 2021, the company announced a $240 million investment to bring a dedicated line of hybrid transaxles to the Putnam plant as part of its plan for producing electrified vehicles in the United States. In February 2022, Toyota announced an additional $73 million investment to expand the transaxle production as well as assemble key electric motor components at the plant.

Since its arrival, Toyota has invested more than $10 million in philanthropic and educational initiatives in West Virginia.