During the late 1700s and early 1800s there was a very high level of emigration to the American and Australian Colonies and newspaper advertisements show emigrant ships sailing regularly from Carsethorn. In 1775 the ''Lovely Nelly'', Captained by William Sheridan, took 82 emigrants to Lot 59 on Prince Edward Island. The reason for the families going was given as being 'to get more bread' - in Scotland they were almost destitute.
A rather grimmer export trade emerged with the transportation of convicts to Australia. They were marched down from Dumfries and housed in the barracks (later a warehouse) at the river's edge. The whitewashed building remains to the south of the bus-stop in Carsethorn.
The coastal trade reached its peak in the late 1840's with almost 25,000 tons entering the river and steamboats such as the ''Countess of Nithsdale'' maintained long established links with Liverpool. It is said that in 1850, 10,000 people emigrated to North America, 7,000 to Australia and 4,000 to New Zealand through the 'Carse', leaving from the jetty which was constructed in 1840 by the Nith Navigation Commission and used by the Liverpool Steam Packet Company. The remains of that jetty still stand beside the deep-water channel at the north end of Carsethorn; apparently it was a triangular structure, whose longest face allowed the steamers a good pierhead to come alongside.