1870 Census Barnhill, Wayne, Illinois (Image 10): Oliver P. Clark, age 51, born in Illinois, a carpenter, lived with Julietta, age 47, born in Ohio, and Edwin, age 26, a carpenter's apprentice, Rachel A., age 22, Omer E., age 20, a carpenter's apprentice, Florence A., age 18, Oscar, age 15, Augusta and Adalaid, age 10, and Marsella, age 8, all born in Illinois.
1880 Census Washington, Ladede, Missouri (District 79): Oliver P Clark, age 61 (born in Illinois, parents born in Con.), farming, lived with wife Juliet, age 57 (born in Ohio, father born in Va?, mother born in Pa), son Edwin J., age 34, and daughter Augusta, age 20, both born in Illinois. On the same page is Oscar Clark, age 25, and his wife Malindy, age 17.