Born in Warren County, Kentucky,[1] Rountree moved north in 1824 to Hillsboro, Illinois,[1] where he served as deputy sheriff. In 1827, he continued north into the Michigan Territory to seek economic opportunity in the leadmining region in the area that is now southern Wisconsin.[1] He staked a claim near the Platte River—where the city of Platteville, Wisconsin, now stands—and discovered rich deposits of lead in the area.[1][2][3][4] He constructed a sod house for himself and, the next year, opened the first lead smelting furnace in the town, the first store, and a log boarding house for newcomers. In 1829 he was appointed the first postmaster for the village and helped organize Platteville's Methodist Episcopal congregation, and in 1836 he established the first sawmill and built the first hotel. In 1841, he platted the original village of Platteville. He also helped establish a creamery and a newspaper there, and had a hand in bringing the Chicago & Northwestern Railway to town in the 1870s.[5][6]
Rountree owned large parcels of land around the village of Platteville and every five or ten years would plat another addition to the village, selling the lots for businesses and homes. Rountree at this time also owned slaves, something that was not legal in the area at the time. His slaves were named Rachel, Maria and Felix. All three were granted their freedom in 1841 by the US Government, although Rachel stayed with Rountree until her death in 1854.[citation needed] In 1853 he built his own fine home on a large parcel south of the downtown. The building still stands, and is now listed as the J. H. Rountree Mansion in the National Register of Historic Places. He had previously built a house for his father-in-law, Samuel Mitchell, now known as the Mitchell-Rountree House, that is also listed on the National Register of Historic Places. Despite its proximity to the downtown, his house remained the only house on that parcel until after Rountree died in 1890, when his heirs subdivided the parcel and the lots quickly filled. The fine homes of the Bayley Avenue Historic District now occupy part of Rountree's home parcel.[6]
He served on the Council (equivalent to a Senate) from the newly created Grant County in the Second through Fourth Wisconsin Territorial Legislatures (1838–1846)[7] and as a delegate to the 1847-1848 Wisconsin State Constitutional Convention from Grant County (where he is recorded as insisting that a strong uniformity clause was "a matter of very great importance".[8]
Rountree was married twice, and had fifteen children.[1] His first wife was Mary Grace Mitchell, the daughter of Reverend Samuel Mitchell, another of the pioneer settlers at Platteville.[11] They married August 7, 1828, at Galena, Illinois, and had five children before her death in 1837.[11] He subsequently married Lydia H. Southworth of Clinton, New York, the niece of New York politician Sylvester Gridley.[11] Rountree and his second wife had ten children.[1]
Though the Northwest Ordinance forbade slavery in the Northwest Territory—including Wisconsin—Rountree bought a woman named Rachael in 1827, in Galena, Illinois, to have her work as a servant to his new wife. "Aunt" Rachael was freed in the 1840s, but stayed with the family until her death. She was buried in the Rountree family plot, under the smallest stone, marked only with an initial "R."[citation needed]
United States