The Hawarden Swing Bridge was a critical component of the railway linking the North Wales coal field to the Mersey.

The Buckley area had a long history of using narrow gauge tramways to connect the various brick and tile works with adjacent collieries. Some of these early lines were extended as far as the River Dee to export the finished product. The first standard gauge railway in the area was the Buckley Railway which was opened in 1862. This ran steeply down from Buckley to Connahs Quay. There it ran onto the docks and to a connection with the London and North Western Railway.

At about this time, industrialists in the Wrexham area were seeking to build a line northwards as an alternative to the GWR. The Wrexham Mold & Connahs Quay Railway was duly authorised to build a line from Wrexham to a connection with the Buckley Railway and in due course they agreed to take over the working of the Buckley Railway. The WM&CQ main line opened in 1866 as a single track. Its original terminus at Wrexham was adjacent to the GWR station (later to become Wrexham Exchange). A passenger service commenced between Wrexham and Buckley but the section beyond, down to Connahs Quay, remained freight only until closure. A period of steady expansion and consolidation followed although at no time could the WM&CQ be described as prosperous.

In the 1880's matters elsewhere had a decisive impact on the future of the railway. The expansionist Manchester Sheffield & Lincolnshire Railway led by Sir Edward Watkin, later to become the Great Central, was keen to tap the traffic of the area. Accordingly it obtained an Act to build a railway from Chester Northgate to Shotton including the bridge over the Dee. To link with this line, the WM&CQ commenced construction of a new line from near Buckley to Shotton. At the same time it doubled its existing line. The result was a double tracked line from Wrexham to Shotton and beyond which today forms the basis of the present service. The Hawarden loop as it was known was opened in 1890.

On the north side of the Dee, a 15 mile line was built from Dee Marsh to Seacombe Ferry via Bidston and opened to passenger and freight traffic in 1896. In 1897 the WM&CQ railway ceased to exist and was merged into the Great Central Railway. The GCR was amalgamated into the London and North Eastern Railway in 1923 and the line to Wrexham became its only outpost in Wales. British Railways took over in 1948 and nowadays under privatisation the service is operated by Arriva Trains Wales.

The swing bridge over the river Dee was in three spans, the northern one being moveable. This was the longest moving span in Britain at 287 ft. (87 m). It was opened in 1889 by the wife of W.E. Gladstone whose residence after which it was named was nearby. The longest in the world carries the railway over the Suez Canal in Egypt.