Duncan McGregor purchased the mountain in the mid 19th century and began building on it in 1872. The area became a popular picnic spot for local church groups and shortly after the ministers named the mountain after him. The cottage was originally opened by McGregor as a hotel. The mountain continued to gain popularity and was eventually sold to a group of investors, William J Arkell and Joseph W Drexel, in 1882. The railroad to the summit was built 1882. The cottage was moved to its current position in 1883 in order to make room for the new, larger hotel, the Hotel Balmoral, which opened in 1884. The hotel could house 200 guests and had electricity, which was rare for the time. The hotel provided many amenities, such as meals and rooms, to the Grant family during their 1885 stay on the mountain.
Since Grant's death
The Mount McGregor Memorial Association was established to take care of the cottage after Grant's death. The cottage opened as a historic site in 1890 with a live in caretaker. The Hotel burned down in 1897 and was not rebuilt. The property was eventually sold to the Metropolitan Life Insurance Company in 1910. They constructed a tuberculosis sanitarium, which was formally dedicated in 1914, and by 1918 twenty buildings had been constructed. In 1945 the sanitarium was converted into a veterans rest camp. New York state eventually dissolved the law chartering the cottage and took ownership. In 1960 the VA camp was repurposed and annexed as the Rome State School for developmentally disabled children. In 1976 the property was again repurposed as a New York State Department of Corrections minimum security prison work camp. In 1981, medium security prisoners began to be housed in the facility. The prison was closed permanently in 2014. In 1985, New York State announced it’s plans to close the cottage at the end of the season. Pressure on the State reversed their decision. The Friends of the Ulysses S. Grant Cottage was formed in the fall of 1989 to operate and take care of the cottage.