Tehachapi Pass played an important part in the race to build the first transcontinental railroad. In the south, construction stopped at Caliente before what seemed an insurmountable barrier, allowing the northern route through Donner Pass to be completed first. William Hood, a construction engineer, later went to the summit of Tehachapi Pass, studied the mountain's contours and grades, and designed a loop so steam engines could climb the steep pass at the entrance to the canyon by crossing over themselves while keeping the grade at 2.2 percent. Trains still pass through a series of tunnels through the Tehachapi Loop and circle the knoll in the center on one of the busiest freight routes in the country. In 1876, when railroad tracks reached the site of the present Tehachapi Depot, a telegraph office became the first structure on the empty plain, four miles east of Tehichipa and one mile east of Greenwich, and the new railroad town was named Tehachapi Summit. By July 1877, four trains passed through Tehachapi daily, two carrying passengers. In 1876, population and early businesses developed along both sides of the tracks, and people moved buildings and houses from old Tehichipa and Greenwich to the new railroad town of Tehachapi Summit. The Erra House Museum at 311 S. Green Street is an example of one of these moved houses. By 1893, a two-story building north of the tracks housed a drug store downstairs and upstairs space for lodges such as the Odd Fellows and the Masons, and the street also had the Franco-American Hotel and Bar and a handball court. By 1885, Southern Pacific had mapped the town, with east-west streets given alpha names and north-south streets given place names, and by then it had hotels, saloons, a post office, and stores.