In Kathryn Grover's informative study of the Underground Railroad in Lowell from 1783 (the year when Massachusetts abolished slavery) to 1863, her area of focus extended to include the area once known as "Black North" in Dracut on "the north shore of the Merrimac River".

She found some specific information about several black families:

Before Lowell was created from agricultural land in East Chelmsford, the population of color in that area had largely settled in Dracut. The 1820 census recorded thirty-four out of a total population in that town of 1,407, four living in the households of whites and thirty living in six black households, the householders of three bearing the surname Lew, those of Zimri, Zeal (Barzillai), and Zadock. [...] Zadock and Zimri were the first and tenth children of Barzillai, who served in both the French and Indian and Revolutionary Wars. Other black household heads in Dracut in 1820 were Moses Freeman, Maria Hartwell, and Frederick Hart (four persons). Ancestors of Freeman and Hartwell had lived in Dracut since as early as the 1770s, and their descendants continued to live in the city through 1850. (Grover)

We are indebted to Kathryn for her research and for allowing us to include it as part of our project.

Grover, Kathryn. The Underground Railroad in Lowell Case Study. Prepared for the Massachusetts Historical Commission and the National Park Service Network to Freedom.

Another important source of information on this topic is Wilbur Siebert's Underground Railroad in Massachusetts. Several pages of his extensive 1935 study describe "Black North". The link below will take you to a section entitled "The Out-bound Underground Traffic Lines of Boston."
Siebert, Wilbur H. "Underground Railroad in Massachusetts." Proceedings of the American Antiquarian Society 45 (April 17, 1935 - October 16, 1935): 25-100.