Simon Gilman lived in Gilmanton/Gilford, NH in and around 1812. Meredith, where he lived in 1800, was called Salem on this 1812 map of New Hampshire, but Meredith on the 1790 census. Town names were in flux as the population grew and towns were established to accommodate the growing number of inhabitants. Each town, obviously, has its history and context depending on when it was established and the people involved. Part of researching my family has involved reading various town histories. Sometimes my relatives have even been the ones to establish the towns. For example, my 6th great grandfather, Jonathan Willard, was the principal founder of Pawlet, VT. Luckily many town histories, such as the one I just referenced for the history of Pawlet, VT, can be found on sites such as Archive.org and Google Books as they are over 100 years old and in the public domain. The Gilman and Willard families would eventually converge with my great grandparents, Augustus Willard Gilman and Nancy Willard. (Yeah, there might be a Willard connection between these two, but I haven’t found it yet.)
Historical maps are also quite useful. I have referenced and used a bunch of them on this blog so far. One good place to find historical maps online is at the David Rumsey Map Collection. The image above is from an 1812 map of New Hampshire within this collection.
Would Simon have recognized this map of New Hampshire?
Smith, Henry Perry, and William S. Rann. “Chapter XXXIII: History of the Town of Pawlet.” In History of Rutland County, Vermont, with Illustrations and Biographical Sketches of Some of Its Prominent Men and Pioneers, 697-719. Syracuse, NY: D. Mason &, 1886. Accessed March 23, 2019. https://archive.org/details/historyofrutland00smit/page/718.