Her older sister Ruth is said to have been the first white, female child born in the newly-settled town of Danbury, Connecticut, British Colonial America. However, if Ruth's birtdate of "about 1684" is correct, the title belongs to Abigail, since Danbury was settled by colonists in 1685, when eight families moved there from what are now Norwalk and Stamford, Connecticut.
When Abigail Barnum was born about 1686, her father, Thomas Barnum, was 62 and her mother, Sarah Thompson, was 45. Abigail married Nathaniel Stevens in 1712, in Fairfield. The couple had at least 6 sons and 2 daughters. Abigail died in 1739, in Danbury, Fairfield, Connecticut, United States, at the age of 54, and was buried in Old North Main Street Cemetery in that town.