The Edinburgh and Glasgow Union Canal Company obtained its first Act of Parliament in 1817 and started building. The point of the canal was simple - move minerals from the mines and quarries of Lanarkshire to the hearths and forges of Edinburgh. The initial cost estimate was wildly inadequate. A second Act in 1819 authorised borrowing of £48,100. A third, in 1821, raised share capital by £50,000. A fourth, in 1823, added another £60,000. By the time the canal opened in 1822 it had cost considerably more than anyone had planned, but the engineering was striking - 31 miles of contour-following waterway from Falkirk to Edinburgh on a single level, no locks needed along the main run, just three remarkable aqueducts carrying the canal across the Avon, the Almond, and the Water of Leith. Joseph Priestley described its purpose plainly in his 1831 Historical Account of the Navigable Rivers, Canals and Railways of Great Britain.

The Edinburgh and Glasgow Railway opened in 1842, twenty years after the canal. The railway ran the same route faster and cheaper. The Union Canal's commercial decline was steady and unstoppable. Commercial traffic ended in 1933. The canal was officially closed in 1965. Through the 1970s and 1980s the remaining stretches sat in a deteriorated state, gradually filling with silt and reeds and rubbish - too useful to fill in, too unused to repair. Then communities along the route began to push back. Restoration work started in the 1990s. The Millennium Link project funded the full reopening of both the Union Canal and the Forth and Clyde Canal, including a new stretch of canal, single and double locks, and a short tunnel under the Edinburgh-Glasgow railway line and the Antonine Wall. As no CAD data existed for the geometry of narrowboats, designers used the turning motion of articulated lorries to calculate the curve of the new bridge approaches. The canal reopened in 2001.

The Wheel opened in 2002. It is the only rotating boat lift of its kind in the world, lifting boats 24 metres between the Union Canal at the top and the Forth and Clyde Canal at the bottom. Each rotation uses the same amount of energy as boiling eight kettles - because the two opposing gondolas balance each other perfectly, the Wheel needs only enough power to overcome friction. A 21-metre wooden barge, the stern of an early- to mid-19th-century horse-drawn freight scow, was unearthed in 2004 on the south bank between the Leamington Lift Bridge and Viewforth Bridge in Edinburgh. Headland Archaeology recorded its construction before dismantling it. It is one of the few physical relics from the canal's working life. The canal is now alive again, used by rowers from George Heriot's, George Watson's, and St Andrew Boat Club; by the Forth Canoe Club; by hire boats from the Edinburgh Canal Society and the Linlithgow Union Canal Society; and by visitors who simply walk the towpath.

Early on Wednesday 12 August 2020, slow-moving thunderstorms parked over eastern Scotland and emptied themselves on the Falkirk area. The Union Canal overtopped its embankment east of Polmont. A 30-metre breach opened. The water that escaped flooded down onto the main railway line from Glasgow to Edinburgh via Falkirk High - Scotland's busiest railway line - and caused significant damage. The canal that had been built to compete with the railway, then beaten by it, then reopened as a heritage waterway, washed out the very railway that had killed its commercial purpose. Repairs took weeks. The story of the Union Canal is the story of British transport history in miniature - built, surpassed, abandoned, restored - and then occasionally reminded, by water and storm, that the original logic of where canals run still matters.