Gainsborough is a market town and civil parish in the West Lindsey district of Lincolnshire, England. The population was 20,842 at the 2011 census, and estimated at 23,243 in 2019. It lies on the east bank of the River Trent, 18 miles (29 km) north-west of Lincoln, 16 miles (26 km) south-west of Scunthorpe, 20 miles south-east of Doncaster and 39 miles (63 km) east of Sheffield. It is sometimes claimed to be England's furthest-inland port.