The first two sections of the circuit were built in 1964 and extended by another mile into September 1965. The extension featured long straights and by virtue of the terrain, a small hill. Nicknamed "the Hump" it gained legendary status during the inaugural 1966 Can Am race. Two drivers in practice found that their cars, both near identical Lola T70 CanAm cars, launched themselves into the air. Both drivers emerged unhurt but were unable to compete in the race. The Canadian winters quickly rendered the track surface very bumpy and as a result, the attrition rate was quite high in the two Canadian Grand Prix Formula One events staged at the circuit. Of the 40 cars entered in those two races (20 each, in 1968 and 1970), 21 reached the checkered flag (with only 16 classified – the rest finishing too far behind the race winners).