In 1699 an Act was passed to improve the navigability of the River Aire (from the River Ouse at Airmyn via Castleford to Leeds) and River Calder (from Castleford to Wakefield). This involved the creation of weirs bypassed by very short "cuts" equpped with locks.
During the 18th century the navigation was improved by longer cuts to bypass difficult or circuitous stretches of river.
The major improvements were made in the last quarter of the century by civil engineers John Smeaton and William Jessop. In particular, the 6-mile Selby Canal connected the Aire at Haddlesey directly with the Ouse at Selby - bypassing the lower reaches of the Aire completely, and forestalling a plan by the Leeds and Liverpool Canal company to construct their own extension from Leeds to Selby.
Selby boomed until the major development of the 19th Century.
In 1826 a wide canal was cut from Knottingley to bypass both the "Selby canal/mid Ouse" route and the whole of the lower reaches of the Aire. The new canal met the Ouse at a point well downstream of Selby, and created the inland port of Goole, easily reachable by large ships coming up the Humber.
The 20th Century saw two major phases of improvement. In 1905, the New Junction Canal connected the Aire and Calder to the Sheffield and South Yorkshire Navigations near Stainforth. In the 1980s the navigation underwent a huge scheme of modernisation in which, all the locks were moderised and enlarged to accommodate the new 600 tonne euro-barge standard. This makes the locks a massive 200' by 20' (70m by 6.1m) - but Doncaster still awaits the large influx of cargoes from Rotterdam !
The Aire and Calder still fulfills its original purpose (although by different routes) by linking Leeds and Wakefield with York, and the Humber (and hence the Trent). More recent canals now also make the A&C a vital link in the English (and increasingly, Welsh) connected inland waterway network.
The current set of links is formidable.
The A&C joins the Leeds and Liverpool Canal at Leeds.
The Calder and Hebble Navigation (from Wakefield) allows boats the reach the Huddersfield Canals and the Rochdale Canal.
The upstream Ouse (reached via the Selby Canal) allows boats to reach York, Boroughbridge and Ripon.
The downstream Ouse (reached via Selby or Goole) connects to the River Derwent and the Humber (and hence Hull, Immingham, and the North Sea).
The S&SYN (reached via the New Junction Canal) forms a link with (in one direction) Doncaster, Rotherham and Sheffield, and (in the other) the tidal River Trent at Keadby.