Jacob Wallace Day, the son of Joseph Day and Margaret Elizabeth Brooks, was born on September 10, 1815 in Grayson County, Kentucky. His parents were already living in the Grayson County area when Grayson County was created from parts of Hardin and Ohio Counties, Kentucky in 1810. At the time of the 1850 Census of Grayson County Jacob W. Day's father, James Day, age 85; and his mother, Margaret Day, age 78; were living with Jacob W. and Amy Ann (Hazle) Day. Amy Ann Hazle was born on May 25, 1822 in the District of Columbia, Virginia (Washington, D.C.). In 1860 he was listed as a carpenter in Falls of Rough.

Amy Ann Hazle and Jacob Wallace Day were married on June 1, 1847 in Daviess County, Kentucky. They were the parents of the following children born in Kentucky:
1. Mary Martha - b. ca 1848 / d. bet 1875-80
-- m. Samuel Kiper
2. Jacob Thomas - b. ca 1849 / d. 1898
-- m. Cynthia Jane Butler
3. Joseph Evan - b. ca 1851
4, William M. - b. ca 1853
5. Charles A. - b. 23 Aug 1854 / d. 10 Aug 1933 -- m. Jane Ellen Boone
6. Margaret E. - b. 20 Feb 1857
7. Rebecca Virginia n. 10 Mar 1859 / d. bet 1877-80 -- m. "Ginnie" m. Jacob Kiper as 1/w bef 1875
8. Robert Walter - b. 1 May 1861 / d. 22 Feb 1937 near Lerna, Coles Co, IL -- m/1. Amamda Y. Kiper; m/2. Julia Catherine Young (1872-1938)
9. Sarah E. - b. 17 Jun 1863 / d. 14 Nov 1919
-- m. Jacob Kiper as 2/w bef 1883

Jacob W. Day's wife, Amy Ann Day, died on August 20, 1875 of consumption. She was buried in the Shain Cemetery near Short Creek, Grayson County, Kentucky. At the time of the 1880 Census of Short Creek, Grayson County, Kentucky the Jacob W. Day family consisted of: the widowed Jacob W., a farmer, age 63, b. KY, parents b. VA; and his daughter Sallie S., a house keeper, age 16, b. KY with parents b. KY.

Jacob W. Day died sometime after the 1880 Census that was taken in June. He was buried with his wife Amy Ann Day in the Shain Cemetery without a date of death given.