The Saxton House, which is the National First Ladies Historic Site, has been rededicated as the McKinley Historic Home as of last Thursday.
This home, the ancestral home of Ida Saxton McKinley (built by her grandfather, George DeWalt, in the 1840s), is now considered a presidential home as well due to the more than twenty years that this was the McKinleys' only permanent residence. During the years that McKinley was in Congress and Governor, the McKinleys used this as their home when the legislature wasn't in session. While the house he and Ida rented, and eventually owned, on North Market Street (which was torn down in the 1930s) is more well known because that is where McKinley conducted his front porch campaign from, it is the Saxton House where they spent the most time. You can read about this house, as well as the research into this matter, in a booklet written by Carl S. Anthony and put out by the National First Ladies Library, "The President At Home" (available by contacting the National First Ladies Library):
One important distinction needs to be clarified about McKinley's home. Although he is usually associated with another house (the "North Market Avenue" house) with a broad front porch, because he conducted his presidential campaign there, he actually lived far longer at the residence familiar to local residents as the Saxton-McKinley House (the "South Market Avenue" house). From September of 1873 to March of 1901, he resided at the Saxton-McKinley house, for stretches of several years to brief stays of several months or days - a period of 28 years. He lived at the North Market Avenue house from Mary of 1871 to August of 1873, February 1896 to March 1897, three months in 1900 and two months in 1901 - only a total of four years and nine months.
Anthony also attests that without the Saxton family, McKinley would not have been president:
The Saxtons helped establish William McKinley in Canton by entrusting him as their legal and business representative, provided a foundation from which he rose political, ensured his unencumbered pursuit of public service with their financial support and provided the house that served as the political base for his social and professional activities. While the Saxton House would never have been come a presidential home had McKinley not lived there, McKinley would never have been president had it not been for the Saxtons.
The McKinleys moved into the Saxton House shortly after the death of Ida's mother, Katherine, and the death of their daughter, Ida. Baby Ida died in the North Market Avenue house. With William's political career on the rise and Ida now in ill health (her health issues date from her second pregnancy), it made sense for the McKinleys to live with Ida's now widowed father and her brother-in-law (as they had been renting the North Market Avenue house from her father anyway) so that Ida would have help with their older daughter, Katie. It was in the Saxton House that Katie died in 1875 of rheumatic heart disease.
There are no extant sources on where the McKinleys lived in the Saxton House, although we do know which room McKinley used as his office. Anthony surmises that the McKinleys lived in a suite on the top floor, where the ballroom had been. This is also where his office was and McKinley always tried to keep his office near where Ida was in any place they stayed, so he could come if she needed help. This house was referred as as a residence of the McKinleys, both in print and by themselves.