The Mannum link was important because of the shipbuilding (paddlesteamers) which was critical to Mannum. Hence the substantive arch railway bridge on the Western Boundary Road, Palmer, near Mannum Waterfalls in the Murraylands. The bridge crosses over the top of Reedy Creek.
The paddle steamers ran on the Murray and Darling Rivers up to 1927 and in the 1870s bales of wool were unloaded at Mannum, to be transported overland to Port Adelaide. However, the importance of Mannum decreased because of the construction of the railway to Murray Bridge in the south (1880s ) and to Morgan in the north (1878). It is only the railway to Murray Bridge that currently exists as it is on the Adelaide-Melbourne interstate line.