According to the Topographical and Historical Sketch of the Town of Andover published in 1822 by Jacob B. Moore, Andover was originally called New Breton in honor of those brave men who achieved the capture of Cape Breton in 1745. Most of the original grantees were out of this expedition. The regimental surgeon, Dr. Anthony Emery, was a college friend of John Phillips, founder of the Phillips Andover Academy in Massachusetts, completed in 1779. The town was incorporated as Andover in that same year. Andover, New Hampshire's first private school, as referenced in John R. Eastman's History of Andover, NH 1751-1906, was started in 1822 and closed in 1828; another was started in 1848 and became Proctor Academy.
Population change for Andover totaled 1,394 over 56 years, from 955 in 1960 to 2,349 in 2016. The largest decennial percent change was a 39 percent increase between 1970 and 1980. The 2016 Census estimate for Andover was 2,349 residents, which ranked 125th among New Hampshire's incorporated cities and towns.The town has 58.4 persons per square mile of land area(info from NHES website)