The source of the Avon is near the village of Naseby in Northamptonshire. For the first few miles of its length between Welford and the Dow Bridge on Watling Street, it forms the border between Northamptonshire and Leicestershire. On this section, it has been dammed to create Stanford Reservoir. It then flows in a generally west-southwesterly direction, not far north of the Cotswold edge and through the Vale of Evesham, passing through the towns and villages of Welford, Rugby, Wolston, Leamington Spa, Warwick, Stratford-upon-Avon, Welford-on-Avon, Bidford-on-Avon, Evesham and Pershore, before it joins the River Severn at Tewkesbury.
The Avon's tributaries include the Rivers Leam, Stour, Sowe, Dene, Arrow, Swift, Alne and Isonbourn as well as many minor streams and brooks.The river is very deep in some places such as before it enters Warwick.
From Alveston weir (2 miles upstream of Stratford-upon-Avon) downstream to Tewkesbury and the River Severn, the river has been rendered navigable by the construction of locks and weirs. The Stratford-upon-Avon Canal links to Avon through a lock in the park in front of the Royal Shakespeare Theatre in Stratford-upon-Avon. Navigation on the River Avon is restricted to boats with a maximum length of 72ft (21.94m), beam of 13ft 6in (4.11m), height of 10ft (3.04m) and draught of 4ft (1.18m).
Traffic is now exclusively leisure oriented. Overnight moorings are available at Stratford-upon-Avon, Luddington, Welford-on-Avon, Barton, Bidford-on-Avon, Harvington , Offenham, Evesham, Craycombe, Wyre, Pershore, Defford, Comberton, Birlingham, Eckington, Strensham and Tewkesbury. There are boatyards at Stratford-upon-Avon, Welford-on-Avon, Barton, Bidford-on-Avon, Evesham and Tewkesbury.
The navigation works on the Avon were originally authorised by an Order in Council of Charles I in 1635, and by 1639 it was reported that the river was navigable to within 4 miles of Warwick. In 1717 the river was divided into two sections, with the Upper Avon Navigation between Alveston to Evesham and the Lower Avon Navigation between Evesham and the River Severn. The Upper Avon Navigation had fallen into disuse by 1874. The Lower Avon Navigation never quite fell into total disuse, but by the end of the second world war only one barge was plying the stretch between Tewksbury and Pershore.
The Lower Avon Navigation Trust Ltd (LANT) was constituted as a charity in 1950, and by 1962 the 8 locks from Tewkesbury to Evesham were restored to working order, re-opening the Lower Avon. The Upper Avon was in a much worse condition than the Lower Avon, but the Upper Avon Navigation Trust Ltd (UANT) was constituted in 1965 to rebuild the navigation. Despite this work requiring the building of new locks and weirs, and most of the work being undertaken by volunteers, the Upper Avon was reopened in 1974.
There are currently proposals to extend the navigation upstream from Alveston to a link with the Grand Union Canal at either Warwick or Leamington. This would open up a stretch of river that has never previously been navigable, and is a controversial issue locally.