Modified racing in America grew out of the post-WWII period when competitors began modifying pre-war coupes and sedans — primarily 1939-1941 models — with stronger engines and stripped-down bodywork for competition on dirt ovals. NASCAR was founded in December 1947 and sanctioned its first event in February 1948, a modified race on the beach course at Daytona Beach, Florida. Red Byron won that inaugural event.
Through the 1950s and 1960s, modified racing spread widely across the northeastern and midwestern United States. Competitors ran cars on both dirt and paved tracks, often switching tires and spring-shock combinations to adapt the same vehicle between surfaces. By the late 1960s and early 1970s, however, the technical requirements for dirt and pavement racing had diverged enough that they became effectively separate categories. NASCAR was no longer sanctioning dirt tracks, and its modified rules evolved toward the paved-track discipline that is today represented by the NASCAR Whelen Modified Tour.
On the dirt side, the DIRT organization was founded by Glenn Donnelly in the early 1970s as a governing structure for northeastern US dirt modified tracks. In 1972 Donnelly created what became the Super DIRTcar Series, initially as a series of qualifier events for the inaugural Super Dirt Week at the New York State Fairgrounds in Syracuse, New York. That event and series grew into the flagship of dirt modified racing in North America.
Dirt modifieds are center-steer machines — the driver sits in the center or left-center of the car — and feature a tubular steel space-frame chassis with exposed front wheels and front suspension. The body panels, fabricated from sheet aluminum or fiberglass, carry only cosmetic references to production car shapes: a manufacturer logo and a body-style logo, neither of which is associated with the actual vehicle manufacturer.
Within the dirt modified world, two primary engine classes define the competitive landscape. Big block modifieds use engines up to 467 cubic inches producing between 650 and 800 horsepower, run on VP Fuels racing gasoline through a four-barrel carburetor. Small block (or 358 modified) cars use 358 cubic inch engines that emerged from NASCAR's old Sportsman division and are particularly prevalent in the St. Lawrence Valley, Hudson Valley, and Twin Tiers region of New York and Pennsylvania. Wheelbase is typically 106 to 110 inches, and minimum weight with the driver is 2,500 pounds for big block cars.
Cars use a two-speed transmission with one reverse gear, a quick-change rear end, a belt-driven dry-sump lubrication system, four-wheel hydraulic disc brakes without power assist, and coil-over suspension on all four corners. Power steering is standard. Hoosier Racing Tires are the spec tire for the Super DIRTcar Series, with the right rear measuring 92.5 inches in circumference.
The Super DIRTcar Series is the premier national touring series for big block dirt modifieds in North America. Operated by World Racing Group since its 2003 acquisition, the series races on dirt ovals primarily in the northeastern United States and Canada, with selected events in Florida and North Carolina. Its crown jewel event, Super Dirt Week, was held at the New York State Fairgrounds mile in Syracuse for decades before moving to a dirt-covered Oswego Speedway in 2016 following the demolition of the Syracuse venue. The Billy Whittaker Cars and Trux 200 at Super Dirt Week pays $50,000 to the winner, one of the largest purses in dirt modified racing. Past broadcasters of Super Dirt Week events have included CBS Sports Network, ESPN, SPEED, TNN, and ESPN2.
The series briefly incorporated asphalt races from 1988 to 1992 at tracks including Cayuga, Flemington, Nazareth, Oswego, Sanair, and Thompson.
Alongside the touring series, the Mr. DIRTcar program recognizes the best overall competitors across weekly dirt track events. Introduced in 1976 as a way to crown an aggregate champion using points from Super DIRTcar Series events and weekly home-track racing, the system has evolved over the decades. Since 2011 the overall title has been determined by a driver's best finishes at their weekly home track, recognizing the local-level excellence that remains central to the dirt modified world.
Brett Hearn holds the all-time record for Super DIRTcar Series wins with 141 victories and the most consecutive seasons with at least one win at 22. Matt Sheppard has won the most DIRTcar titles with ten championships.