The roots of the venue trace to 1961, when Keith Bryar opened the 106 Midway Raceway, a quarter-mile dirt oval adjacent to New Hampshire Route 106. In 1964, Bryar negotiated rights to build a road course to attract the Laconia Classic motorcycle event. The resulting 10-turn, 1.6-mile Bryar Motorsports Park road course opened in June 1965. The venue thus carried a road course as a core feature from its earliest years as a major facility, decades before the oval was constructed.
When Maine businessman Bob Bahre purchased the facility in December 1988 for $950,000, he undertook a complete reconfiguration to attract national racing series. The road course was rebuilt as part of this overhaul. NHIS' road course officially reopened on June 15, 1990, for the Loudon Classic weekend. Motorcycle racers consistently found the track challenging due to limited run-off areas, and the circuit attracted significant criticism on safety grounds in its early years under Bahre's ownership.
The road course at NHMS measures 1.600 miles (2.575 km) with 12 turns. It is formed by integrating specialized road course sections with portions of the oval track. A second infield road course configuration was added in 2005 primarily for motorcycles; because of concerns about tire wear on the banked oval sections, oval turns 1 and 2 were bypassed on this variant, producing a length of 2.950 miles (4.748 km). The Daytona 200 equivalent event at the venue uses a variant that bypasses the main car version of certain corners, substituting a tighter hairpin for motorcycle-specific geometry.
Since 1965, NHMS has hosted the Loudon Classic, one of the oldest and most significant motorcycle racing events in the United States. Until 2001, the event incorporated AMA Superbike Championship races. The road course portion of the venue has long been synonymous with the Loudon Classic weekend, giving NHMS a dual identity as both a NASCAR oval and a major motorcycle facility.
The road course has also hosted the Trans-Am Series from 1966 to 1972 and a single IMSA GT Championship round in 1972, during the Bryar Motorsports Park era.
In May 2000, a significant safety crisis struck the oval section when Busch Series driver Adam Petty crashed into the third-turn wall after suffering a stuck throttle during practice. Two months later, NASCAR Cup Series driver Kenny Irwin Jr. died in a nearly identical accident at the same location. The incidents prompted modifications to the turn radius and banking and raised broader questions about track safety. Repaving in 2002 widened the turns by 12 feet and reduced banking from 12 degrees to 6 to 7 degrees. SAFER barriers were installed in 2003. A further fatality on the road course — motorcycle racer Morgan Rose in the 11th turn — occurred in 2010.
Speedway Motorsports, Inc. (SMI), owned by Bruton Smith, acquired the venue from Bahre on January 11, 2008, for $340 million. The facility was renamed New Hampshire Motor Speedway at that time. An infield renovation project completed in 2009 expanded road course and paddock infrastructure by removing wetlands and trees. In recent years, the venue has significantly reduced grandstand capacity, from a peak of 91,000 to 44,000 as of 2024, reflecting declining attendance trends at NASCAR events.
The road course itself remains a consistent feature of the NHMS calendar, anchored by the Loudon Classic and supplementary motorcycle championships.