Thor Industries, Inc., was founded on August 29, 1980, when Wade F. B. Thompson and Peter B. Orthwein acquired Airstream, the most recognized name in the industry. Despite its venerable image, Airstream had not fared well during the economic downturn of the late 1970s. By focusing on improving quality while reducing costs, Airstream had returned to profitability in its very first year under the new Thor management.

By 1982 Thor was strong enough to purchase the Canadian company General Coach, which manufactures travel trailers and fifth wheels in Hensall, Ontario, and Okanagan, British Columbia.

In 1984 Thor became a public company and in 1986 was listed on the New York Stock Exchange. That same year, Forbes Magazine ranked Thor sixth out of the "200 best small companies in America."

In 1988, Thor entered the small and mid-size bus industry with the acquisition of ElDorado Bus. In 1991, National Coach was purchased and the two companies operated under the ElDorado National trademark, with plants in California and Kansas.

Also in 1991 Thor acquired Dutchmen Manufacturing, now one of the leading brands of travel trailers and fifth wheels. Four Winds International, manufacturer of Class A and Class C motorhomes, was acquired in 1992. Komfort Corporation, builder of trailers and fifth wheels, became part of the growing Thor family in 1995. 1996 saw the start-up of Thor California, which became one of the most successful RV start-ups.

In 1998, Thor solidified its leadership in the bus industry with the acquisition of Champion Bus.

When Thor joined forces with Keystone RV in 2001, the company achieved an unprecedented dominance within the RV industry. With the acquisition in 2003 of Damon, manufacturer of Class A motorhomes, and Breckenridge, builder of park trailers, and the addition of Crossroads RV in 2004, this dominance was complete.

In 2005, Thor acquired Goshen Coach to round out its holdings in the small and mid-sized bus industry.

Finally, in 2010, Thor made two substantial acquisitions. In March, 2010, it acquired SJC Industries, Inc, the second largest ambulance manufacturer in the United States. Then, in September 2010, Thor made its largest acquisition to date when it purchased Heartland RV company, further cementing its position as the world's largest producer of towable RVs.