Short answers, pulled from the story.
Newburyport was incorporated on the 28th of January 1764, when the General Court of Massachusetts passed an act separating part of Newbury into a new town. Governor Francis Bernard approved the act on the 4th of February 1764.
Newburyport abolitionists, many of them mariners, used the city's port connections to help enslaved people escape. Captain Alexander Graves smuggled enslaved people from the South to Canada. William Lloyd Garrison, one of America's most prominent abolitionists, was born in Newburyport in 1805.
Yankee Homecoming is an annual week-long festival initiated in 1957 by native Newburyporter George Cashman to stimulate the local economy. First held in 1958, it is the second-oldest homecoming festival in the United States and includes over 200 events, nightly concerts, road races, and a fireworks show.
By 1970, Newburyport's historic downtown was scheduled for demolition and federal redevelopment after strip malls and new highways had drawn businesses away from the city center. The city reversed course at the last moment, signing a federal grant to preserve its historic architecture instead, with renovation running through the 1970s.
Lovecraft based his fictional decaying port city of Innsmouth largely on Newburyport. The actual city appears in the story's opening chapter when the narrator departs from it on his way to Innsmouth.
Notable people born in Newburyport include abolitionist William Lloyd Garrison (1805), shipbuilder Donald McKay (1810), Nobel Prize in Chemistry recipient Robert S. Mulliken (1896), polar explorer Adolphus Greely (1844), and actor Joe Keery (1992). John Quincy Adams, who became U.S. president, lived in the city from 1787 to 1788.