The physical layout of Clane, that the long Main Street, with its well aligned buidings, would normally suggest eighteenth century town planning. There is good reason to believe however, that despite its planned appearance, Clane evolved in response to a combination of purely natural factors of an unusual nature. The Main Street in Clane is built along a broad, relatively flat sand ridge where an esker ridge peters out in the Liffey valley. The course of this former sub-glacial stream can be traced some two and a half miles southwards from Boherhole Cross. Prior to the 1940s when the hydroelectric dam was built on the Liffey at Poulaphuca, flooding was a perennial problem in Clane. Flood waters regularly came up through the back yards as far as the Dublin Road. In times of particularly bad flooding only the main street would have stood above water level, together with the houses on either side of it, tucked up as tightly as they are on the sloping sides of the ridge. To appreciate this, an observer will note how the yard entrances from the street drop steeply down from street level, particularly on the northern end of the street. The same basic lay-out as exists today can be seen on the earliest street map, that of Noble and Keenan of 1752. The late eighteenth and nineteenth centuries brought a great communications boom and Clane narrowly missed out on two canals and two railways, passing as they did to the north and south of us. Ironically, Clane had stood to gain from an even earlier and almost equally ambitious scheme which proposed to open up a new road to Limerick, passing behind the Slieve Bloom Mountains and not alone cutting seven miles off the existing route but providing an alternative route which would have been much more easily negotiable to horse transport. The scheme was the brainchild of one Moss, a past President of the Institution of Engineers of Ireland. He succeeded in having a Turnpike Act of George III passed in 1752. The road came through Clane, and it was proposed that it be constructed in a dead straight line, irrespective of terrain, bypassing Edenderry. It was not begun until 1770, a time when road transport with unsprung coaches was loosing popularity in face of the new found enthusiasm for the canal project. The road as it came through Clane was a marvelous improvement, but the whole project fell through when the new road had reached only Derrybrennan, on the road to Rathangan.

So Clane retained its function in the nineteenth century of a small local service centre and market village. The traditional patterns of trading flourished, principally the combined pub and grocery, doing in addition a general trade in hardware, footwear, etc. A successful local businessman, James O'Neill, succeeded in the course of a lifetime, in buying out a majority stake in the town, including the post office. The population in the last century was in fact, greater than in the early decades of this one. The eighteenth century brought slow but steady improvements, including the arrival of the Presentation Sisters in 1838, the establishment of the Boys' and Girls' National Primary Schools in the same year to replace a number of Parish and privately run schools. In 1882 the Hewetson School moved from Betaghstown to Millicent, amalgamating with the Protestant Parish School. In 1883, the Church of St. Michael and All Angels was built in Millicent. In 1884, the Church of St. Patrick and St. Brigid was built in Clane on the site of a smaller church built in 1805. In the same year, G.A.A. was founded in Clane. Politically, the last century was relatively quiet. Ribbonism was strong at the beginning of the century, while the Land League agitation for proprietor ownership of the land attracted widespread support in the closing decades.