Fontana is a city of 207,460 residents in San Bernardino County, California. Founded by Azariel Blanchard Miller in 1913, it remained essentially rural until World War II, when entrepreneur Henry J. Kaiser built a large steel mill in the area. It is now a regional hub of the trucking industry, with Interstate 10 and State Route 210 transecting the city from east to west, and Interstate 15 passing diagonally through its northwestern quadrant.It is home to the largest of the San Bernardino County system libraries, a renovated historic theater, a municipal park, and the Auto Club Speedway on the site of the Kaiser Steel Mill. Fontana also hosts the Fontana Days Half Marathon and 5K run. This race is the fastest half-marathon course in the world.The United States Census Bureau estimated Fontana's 2016 population at 207,460, making it the second most populous city in San Bernardino County and the 19th largest in the state.