Historically Speaking: Dover has its own history of slavery Tony McManus Back in 1775, Colonial authorities in New Hampshire took a census of its inhabitants and reported the total number of people then in Dover as 1,666. There were 410 males under the age of 16, 786 females, 342 males between the ages of 16 and 50 not in the army, and 74 males over the age of 50, a decidedly young population. In addition, there were 342 males "gone in the army," a decidedly large percentage of the whole. There was one final category: 26 "negros and slaves for life". There may not have been an organized slave trade in New Hampshire in those years, but there was considerable commerce between the Seacoast and various Caribbean islands, being the source for much of the slave population in the Southern Colonies. But there were individuals who would be brought to Portsmouth and purchased by some of the wealthier families in the area, more so there than in Dover.