In 1749 this territory was chartered as Monadnock Number 2, sometimes called Middle Monadnock or Middletown. It was one of the first towns established under the New Hampshire proprietors' purchase of undivided lands under the Masonian claim. The grant was renewed in 1767, and the town incorporated in 1773 as Jaffrey, in honor of George Jaffrey, member of a prominent Portsmouth family. Both his father and son were named George, and all three served as treasurer of the province. George Senior held the position when the state was still under Massachusetts rule. George III also served as proprietors' clerk, and was a life trustee of Dartmouth College, providing the design for the official college seal.
Population change for Jaffrey totaled 2,091 over 56 years, from 3,154 in 1960 to 5,245 in 2016. The largest decennial percent change was a 30 percent increase between 1970 and 1980, followed by a 24 percent increase over the next decade. The 2016 Census estimate for Jaffrey was 5,245 residents, which ranked 66th among New Hampshire's incorporated cities and towns. This town has 136.6persons per square mile of land area.(info from NHES website)