The city has the largest population in the country and 'in addition' [='also, additionally'] is a major shipping port.
an 'addition to' the family [=a new member of the family, such as a newborn baby]
The soup was thickened by the 'addition of' cream in the last stage of cooking.
(..) There are no breasts on this anatomy model. There are no eyes or mouth either, but we were told to draw in the face. Well, your unnecessary anatomical additions got the Ellis boy thoroughly overexcited. He stole my drawing. Yes, and now there are pictures of naked women all over this school. (..)2009 The Lovely Bones