Sebring International Raceway

Sebring International Raceway was laid out on the runways of Hendricks Army Airfield, a B-17 pilot training base in operation from 1941 to 1946. The circuit still runs on old sections of those World War II-era landing fields, constructed of concrete sections with large seams.

Those seams are the reason Sebring is renowned for its rough, bumpy and changing surfaces. The transition between smooth modern asphalt and the original airfield concrete punishes cars and drivers across the full twelve hours — a Sebring car has to be built to survive the bumps, not just to be fast, and the race is widely treated as the toughest test of reliability on the IMSA calendar.

Sebring is one of the oldest continuously operating race tracks in the U.S., its first race run in 1950. The inaugural 12 Hours of Sebring was held on 15 March 1952, and the race has been a fixture of international sportscar racing ever since.

Run once around the clock — starting in daylight and finishing under the lights — Sebring has hosted the world championship, the World Sportscar Championship, the American Le Mans Series and now the IMSA WeatherTech SportsCar Championship across its history.

Wikipedia frames Sebring as part of the informal Triple Crown of endurance racing alongside the 24 Hours of Le Mans and the 24 Hours of Daytona. For decades it has functioned as the spring endurance test that European and American teams use to prepare for Le Mans in June.

The combination of a long race, a punishing surface and a March date makes Sebring the place where a new car's reliability is established before the bigger summer enduros — the reason a Sebring win carries weight well beyond the IMSA championship points it pays.