Here's a starting point. You should be able to go backwards and forwards through other online resources with this info.
09/12/1918 World War I Draft Registration for Coos County, New Hampshire
George Kelley NELSON, white, 37, native-born 07/09/1881
Residing in Groveton, Coos County
Working as a Paper Maker for Odell Manufacturing Company of Groveton
Nearest Relative: (Ann?) Mabel NELSON of Groveton
Physical Description: 5'-6" tall; medium build; brown eyes; brown hair; no disabilities.