Which is the only London Underground line to cross the Thames river over a bridge?

The District line is a London Underground line that runs from Upminster in the east to Earl's Court in west London, where it splits into a number of branches. One branch runs to Wimbledon in south-west London, one runs north to Edgware Road, and a short weekends-only branch runs one-stop to Kensington (Olympia). The main route continues west from Earl's Court to Turnham Green after which it divides again into two western branches to Richmond and Ealing Broadway.

Coloured green on the Tube map, the line serves 60 stations over 40 miles (64 km), and with bridges across the River Thames on the Wimbledon and Richmond branches it is the only Underground line to cross the river in this way. The track and stations between Barking and Aldgate East are shared with the Hammersmith & City line, and between Tower Hill and Gloucester Road and on the Edgware Road branch they are shared with the Circle line. Some of the stations between South Kensington and Ealing Common are shared with the Piccadilly line. Unlike London's deep-level lines, the railway tunnels are just below the surface, and the trains are of a similar size to those on British main lines.