In 1880 17-year-old Harriet Seymour lived with her parents, T.H. Seymour and Louisa Abell, six siblings and two servants at 5624 N. Newark Ave., Norwood Park, Chicago. Her father was a prominent member of Chicago's Board of Trade. The Seymours built the Italianate addition to the original house in 1868 to accommodate their large family. Harriet and her siblings played in the estate's vineyards and apple and cherry orchards. The Noble-Seymour-Crippen House is now a Chicago landmark and museum.
In 1900, Harriet, at 37, was the only one of her siblings still living with their parents in the Norwood Park house. Three years later, she was briefly married to Canadian immigrant Albert E.D. Carscallen. They were married and lived in Phoenix, Arizona. On a trip to Albert's hometown of Belleville, Ontario, perhaps for Christmas, Albert died in an accident on December 30, 1903. After Albert's death, at some point Harriet returned to Chicago to live. 
Following the 1919 death of her aunt, Katherine Seymour Brown, Harriet lived with her uncle, William Liston Brown, in Pasadena, California. Brown, a wealthy financier, died in 1929 leaving most of his estate to Harriet, much to the chagrin of his other relatives. They contested the will, won the case, but lost on appeal. 
Harriet died in 1952 and was buried at Union Ridge Cemetery, Chicago.
↑ "United States Census, 1880," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MXJ4-X5N : 15 September 2017), Hattie Seymour in household of T H Seymour, Norwood Park, Cook, Illinois, United States; citing enumeration district ED 214, sheet 114B, NARA microfilm publication T9 (Washington D.C.: National Archives and Records Administration, n.d.), roll 0201; FHL microfilm 1,254,201.
↑ "United States Census, 1900," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MSQV-CJH : accessed 23 September 2017), Harriet L Seymour in household of Thos H Seymour, Precinct 1 Chicago city Ward 27, Cook, Illinois, United States; citing enumeration district (ED) 818, sheet 12B, family 216, NARA microfilm publication T623 (Washington, D.C.: National Archives and Records Administration, 1972.); FHL microfilm 1,240,277.
↑ "Arizona, Marriages, 1865-1949," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/FQ2Z-NML : accessed 23 January 2015), Albert E. D. Carscallen and Harriett Louise Seymour, 03 Jun 1903; citing Mesa, Maricopa, Arizona, reference 360, index based upon data collected by the Genealogical Society of Utah, Salt Lake City; FHL microfilm 1,955,735.
↑ "New York, Passenger Arrival Lists (Ellis Island), 1892-1924," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/JJ4Q-8WY : accessed 23 January 2015), Harriet Carscallen, 08 Mar 1915; citing departure port Naples, arrival port New York, ship name Duca Degli Abruzzi, NARA microfilm publication T715 and M237 (Washington D.C.: National Archives and Records Administration, n.d.).
↑ Birth and Death Dates: "California, Death Index, 1940-1997," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/VP76-8KY : accessed 23 January 2015), Harriet Seymour Carscallen, 29 Feb 1952; Department of Public Health Services, Sacramento.