Speedway Motorsports, Inc. (SMI) is an American corporation that owns and manages racing facilities that host NASCAR, IndyCar Series, NHRA, World of Outlaws and other motor racing series. The company's headquarters are located at Charlotte Motor Speedway, in the suburbs of Charlotte, NC. SMI owns nine racing facilities with a combined seating capacity of approximately 885,000. In addition to operating racetracks, SMI owns Performance Racing Network (PRN), U.S. Legends Cars International, and co-owns Motorsports Authentics.

Speedway Motorsports didn't officially incorporate until 1994. Bruton Smith began building SMI in the 1950s when he worked as a race promoter and eventually built Charlotte Motor Speedway in 1959. Smith left the racing business in the early 1960s to pursue other business ventures. He became very successful and by 1975 had owned majority shares in CMS and took over as CEO. A year later he appointed H.A. "Humpy" Wheeler as general manager. Smith began to expand CMS, adding additional grandstands and facilities including condominiums, a first for a sports facility.

In 1990, Smith began to acquire additional speedway properties beginning with Atlanta Motor Speedway. As he did with Charlotte, Smith began expanding seating and facilities at Atlanta. In 1992, lights were added to CMS, making it one of the first speedways to offer night racing, and the company developed the Legends car racing circuit, now called U.S. Legend Cars International. Smith incorporated Speedway Motorsports in December 1994, and in February 24th, 1995 took the company public by offering shares of stock, debuting at $18 per share.

In 1996, SMI began to quickly expand, acquiring two additional facilities; Bristol Motor Speedway and Sonoma Raceway. A year later, the company finished construction of the $250 million, 150,000 seat Texas Motor Speedway. Between 1993 and 1998, SMI had increased its total seating capacity from 176,000 to 551,000. In 1999 SMI outbid rival International Speedway Corporation (ISC) to purchase Las Vegas Motor Speedway. Smith had outbid ISC by $15 million to make a total $215 million purchase. That same year, SMI sold the naming rights of its flagship Charlotte Motor Speedway to Lowe's, a $35 million deal that would last until 2009.

Until 1999, Speedway Motorsports was the top track owner in the motorsports industry. That year, International Speedway Corporation, then the second largest track owner, acquired Penske Motorsports, then the third largest track owner. The $623 million deal propelled ISC to the top track owner, and SMI fell to second. Smith then turned his attention towards securing two NASCAR dates at each of his facilities. As of 2011, only four SMI owned tracks hold two NASCAR dates.

SMI purchased North Wilkesboro Speedway and New Hampshire Motor Speedway in 2007, and in 2008 purchased Kentucky Speedway. Today SMI owns nine racing facilities, eight of which are used to host major racing series including NASCAR, IndyCar and NHRA. As of December 31, 2009, the combined total permanent seating capacity was approximately 885,000. In 2011, SMI owned tracks will host 12 of the 36 NASCAR Sprint Cup Series races, including three Chase races, plus the Sprint All Star Race.

In addition to speedway properties, SMI also owns Performance Racing Network, a radio network that broadcasts all NASCAR races at SMI owned tracks. SMI also equally owns Motorsports Authentics, a joint venture formed with International Speedway Corporation, to produce, market and sell licensed motorsports merchandise.

SMI has a history of purchasing tracks to obtain NASCAR race dates. The company's purchases and closures of the tracks in order to obtain a second NASCAR date for Texas Motor Speedway led to the Ferko lawsuit.

In 1996, the company purchased half interest in North Wilkesboro Speedway in North Wilkesboro, North Carolina along with Bob Bahre of New Hampshire International Speedway (now New Hampshire Motor Speedway). SMI moved one of North Wilkesboro Speedway's dates to Texas Motor Speedway and Bob Bahre moved the second date to his facility. On November 2, 2007, SMI purchased NHIS and part of the purchase resulted in SMI gaining full ownership of North Wilkesboro Speedway.

In 2004, as a result of the Ferko lawsuit, SMI gained ownership of the North Carolina Speedway in Rockingham, North Carolina. SMI closed North Carolina Speedway and moved the track's final race date to Texas Motor Speedway. On October 2, 2007, SMI sold North Carolina Speedway at auction. The track was purchased by "Indiana" Andy Hillenburg for $4.4 million, and renamed Rockingham Speedway.

On November 2, 2007, SMI announced the purchase of New Hampshire International Speedway from Bob Bahre, and renamed the facility New Hampshire Motor Speedway. This has led to speculation that SMI would move one of New Hampshire's dates to Las Vegas Motor Speedway and/or swap the date with the fall race at Texas Motor Speedway (TMS has expressed an interest in moving the fall race away from the first weekend in November, which is also the opening weekend of deer hunting season in Texas). In 2018, the fall race weekend will be moved to Las Vegas.

On May 22, 2008, SMI announced it had purchased Kentucky Speedway from Kentucky Speedway, LLC. It was purchased from Joie Chitwood. The track had been trying to secure a NASCAR Sprint Cup race for several years. SMI was finally victorious in their pursuit, with Kentucky Speedway receiving its inaugural Sprint Cup race on July 9, 2011. It appears this came at the expense of SMI-owned Atlanta Motor Speedway, which dropped from two races to one on the 2011 Sprint Cup schedule.