The River Soar is a major tributary of the River Trent in the English East Midlands and is the principal river of Leicestershire. The source of the river is midway between Hinckley and Lutterworth. The river then flows north through Leicester, where it is joined by the Grand Union Canal. Continuing on through the Leicestershire Soar Valley, it passes Loughborough and Kegworth until it reaches the Trent at the county boundary. In the 18th century, the Soar was made navigable, initially between Loughborough and the Trent, and then through to Leicester. It was not until the early 19th century that it was linked by the Grand Union Canal to the wider network to the south and to London.