Lydia Hartwell after Joseph's death in 1849
Upon the death of her husband Joseph in the Gold Rush in 1849, Lydia Parker Hartwell became a 29-year old widow living in Salem, Massachusetts, with her four young sons: Joseph b. 1839, William b. 1845 (my great-great-grandfather), George b. 1847 and Daniel b. 1849.
Lydia Hartwell's residence in Salem
According to the 1857 Salem City Directory, Lydia Hartwell, widow, lived at 7 Park in Salem.
I was able to locate an 1856 map of Salem created by Henry Francis Walling, and have pinpointed the location of Lydia's house below. Note the proximity to Salem Harbor - I think it likely that Lydia and her young boys lived there while Joseph was away at sea.