‘By the time of the 1851 census Sunderland Borough encompassed the whole of Sunderland, Monkwearmouth and Bishopwearmouth and was home to 63,897 people. Of the trades and professions represented in the town, seamen were the biggest group with 3,060 sailors resident in the town. Shipwrights (shipbuilders) were the next biggest group with 2,025 employed in this trade.'
Some Useful and Interesting Sources
Street Maps of Sunderland in 1860 http://www.durham-images.org/public/ms/spin.html
Sunderland: A History of the Town, Port, Trade and Commerce
Personal recollections written by Taylor Potts of Sunderland in 1892
Looking for Durham Ancestors? I thoroughly recommend using Durham Records Online as their records contain full transcripts which often yield far more information than other online indexes.