Brazil prospered because of its location on the National Road, and when the road was designated US 40 in 1926 the town became more closely linked with the rest of the nation through a vital economic corridor that connected places such as Baltimore, Kansas City, and California. Brazil's brick and coal industries fueled much of its growth in the late 19th and early 20th centuries, and in the early 20th century most of the bricks used to pave the National Road across Indiana were manufactured there. Brazil grew from a stage line relay station into the county seat of Clay County, surpassing Bowling Green, which lay too far from the National Road to continue to prosper. Before Interstate 70 was completed, travelers on US 40 passing across Indiana and the United States had to go through Brazil, helping sustain a vibrant economy and thriving downtown. Brazil's bricks also paved the Indianapolis Motor Speedway, originally built in 1909 as a test track for the modern automobile, where about 3.2 million bricks from Brazil were later covered with asphalt in 1939, though a small stretch was restored in 1961 with more than 500 bricks dating from 1909. The automobile revived the National Road in the 1920s as cars and trucks increased demand for paved all-weather highways, and the old road became one of the first routes numbered in the new federal system as US Route 40, a transcontinental highway from Atlantic City to San Francisco. Gas stations, diners, and motels brought new prosperity along the route, which remained one of the country's primary east-west roads until Interstate 70 was completed in the 1970s. The National Road continued to shape transportation and commerce, from the 1841 Huddleston Farmhouse in Cambridge City to the Indiana-based Studebaker company, which evolved from an 1868 blacksmith shop into the world's largest wagon manufacturer and later successfully shifted from horse-drawn vehicles to electric and gasoline-powered cars.