This territory was first granted in 1752 by the Masonian Proprietors as Monadnock Number 5. On some early maps, the town was called Oxford, and was referenced as New Marlborough in early state documents. Many of the settlers were from Marlborough, Massachusetts, which had been named for John Churchill, Duke of Marlborough, in the late 1600s. The town was incorporated as Marlborough in 1776. At one time there was a thriving granite quarrying industry in Marlborough.
Population change for Marlborough totaled 431 over 56 years, from 1,612 in 1960 to 2,043 in 2016. The largest decennial percent change was a 10 percent increase between 1970 and 1980; the four other decades had increases of five percent or less. The 2016 Census estimate for Marlborough was 2,043 residents, which ranked 140th among New Hampshire's incorporated cities and towns. This town has 100.1 persons per square mile of land area. (info from NHES website)