The world’s first subway line opened in London in 1863. It was 3.75 mi (6 km) long and soon carried tens of thousands of passengers each day—transporting 9.5 million in its first year. Initially steam-powered, the system first electrified some of its lines in 1890. By 1896, it was fully electrified. Today, the London Underground system is one of the largest in the world, with 256 miles (410 km) of track and 270 stations. How many passengers did it carry on January 10, 1863? Discuss