In 1853 he and his doctor brother John moved to Weston, Missouri in Platte County just across the Missouri River from Fort Leavenworth, Kansas. B.F Stringfellow practiced law with Peter T. Abell and published the pro-slavery Squatter Sovereign with his brother. In 1854 after four slaves from Platte County ran away to Leavenworth, they organized the Platte County Self-Defensive Association to attempt to prevent Free-Stater settlement of Kansas. The Stringfellow brothers also stumped western Missouri organizing "blue lodges" along the entire Kansas border. The brothers, working with David Rice Atchison, attempted to get residents of Southern states to move to Kansas with their slaves to counter settlements by the anti-slavery Massachusetts Emigrant Aid Company. B.F. Stringfellow also issued "Stringfellow's Exposition," which said Missourians could vote in Kansas as it decided whether to enter the Union as a free state or a slave state. Stringfellow's positions as General in the Missouri Militia increased his opinion's clout. The New York Tribune quoted him in an 1855 speech in St. Joseph, Missouri:
On July 2, 1855, he was accused of attacking Kansas Territory Governor Andrew Horatio Reeder at Reeder's office in the Shawnee Methodist Mission in Fairway, Kansas. The free state version of the encounter says: The slave state version said that Stringfellow told the governor: Bloodshed would occur on both sides of the Missouri-Kansas border in the Bleeding Kansas skirmishes as attempts were to influence how the state entered the union with 5,000 Missourians voting in one Kansas election alone.
In 1859 after Kansas entered as a free state, Stringfellow moved to Atchison, where he continued to practice law, although his brother John temporary returned to Virginia to settle their father's estate. The Stringfellow brothers organized the Atchison and St. Joseph Railroad Company and B.F. Stringfellow became company attorney. B.F. Stringfellow also performed legal work for the Kansas City, St. Joseph & Council Bluffs Railroad, and the Kansas and Western Missouri Railway Company. During the Civil War, age prevented him from enlisting, and the Platte Bridge Railroad Tragedy and defeats of the Missouri State Guard may have changed his proslavery sympathies. B.F. Stringfellow continued his law practice through the war and concentrated on promoting the area's economic development. He worked with former antislavery adversary Cyrus K. Holliday, who had organized the Atchison and Topeka Railway Company in 1859, which reorganized in 1863 as the Atchison, Topeka and Santa Fe Railway. Using their political connections and funds allotted by the Pacific Railroad Acts, they connected their lines to the First Transcontinental Railroad at Council Bluffs in 1869. Three years later Topeka became the eastern terminus for the second transcontinental route, which ended in Los Angeles. B.F. Stringfellow died at the home of his daughter in Chicago, Illinois on April 26, 1891.
