Editing Aire and Calder Navigation (section)

===Development===
Some development of the navigation occurred. In 1744, the undertakers bought some land at Airmyn, and developed warehousing and wharfage there, as a more convenient point than Rawcliffe, where the water was shallower. In the 1760s, £13,000 was spent on improvements and maintenance, with several weirs being rebuilt to improve the depth of water. There was a long-running dispute with Arthur Ingram, who owned Knottingley mill, which started in 1731, and was not finally resolved until 1776, when the company bought both of Ingram's mills. Despite this, the general profitability of the navigation led the undertakers to be complacent about its development. They asked [[John Smeaton]] to suggest improvements in 1771, but the subsequent attempt to authorise such improvements was disputed in Parliament on the basis that the present navigation was totally inadequate. The recently finished [[Calder and Hebble Navigation]] proposed to build a canal from Wakefield to the Dutch River, which would bypass the Calder completely, and the [[Leeds and Liverpool Canal]] supported a Leeds to Selby canal, which would bypass the Aire. During 1772, they asked Smeaton to survey a route to avoid the lower Aire, but his assistant, [[William Jessop]] actually carried out the work. He proposed a {{convert|7+1/4|mi|km|adj=on}} canal from Haddlesey lock to the Ouse at Newland. With Parliament not reaching a decision, they reworked their plan, which was now for a {{convert|5+1/4|mi|km|adj=on}} canal from Haddlesey to [[Selby]], with a new cut from Ferrybridge to Beal, and improvements above Castleford. In 1774 the Leeds to Selby bill was rejected by Parliament, but the Aire and Calder bill was passed as the [[Aire and Calder Navigation Act 1774]] ([[14 Geo. 3]]. c. 96) with a few amendments.<ref>{{harvnb |Hadfield |1972 |pp=22–34}}</ref>

Construction of the [[Selby Canal]] began in 1775, and it was opened on 29 April 1778. The new cut at Castleford opened in spring 1775, while those at Knostrop and [[Hunslet]] were finished in 1779. [[Methley]] cut was completed, but [[Woodlesford]] was not, as the company bought the mill there instead. All locks were replaced, and the total cost was over £60,000, of which around £20,000 was for the Selby Canal. The navigation remained profitable, paying £9,000 in dividends in 1775, which had risen to £32,000 by 1791. Most traffic now used the Selby route, and the transhipment facilities at Airmyn were closed in 1779.<ref>{{harvnb |Hadfield |1972 |pp=34–37}}</ref>

Selby was the upper limit for seagoing ships at the time, and became a major transhipment port for the smaller boats using the canal. Canal boats were limited to about 60 tons, whereas ships of up to 200 tons could reach Selby. By 1800, it was handling some 369,780 tons of goods, and the support industries of ropemaking, sailmaking and shipbuilding were expanding.<ref>{{harvnb |Hadfield |1972 |pp=37–39}}</ref>