Crozier was born in Knoxville on February 10, 1812, the youngest son of Captain John and Hannah Barton Crozier. Crozier's father, an immigrant from County Fermanagh in Northern Ireland, was among the earliest settlers in Knoxville, and served as Knoxville's postmaster from 1804 until 1838. Peggy Barton Crozier, was the eldest daughter of John and Hannah Barton Crozier, and had married Dr. J.G.M. Ramsey on March 1, 1823 while her parents were then residing at Fruit Hill. After attending public schools, the younger Crozier graduated from East Tennessee College in 1829. He was admitted to the Tennessee bar, and practiced law in Knoxville. In 1835, after Knox County attorney-general John Nelson resigned, Crozier was appointed to fill out his term. From 1837 to 1839, Crozier represented Knox County in the Tennessee House of Representatives. In 1839, he was elected to Knoxville's Board of Aldermen, and in 1844, he was a presidential elector for the Clay/Frelinghuysen ticket. Crozier was elected to the Twenty-ninth and Thirtieth congresses, serving from March 4, 1845 to March 3, 1849. During the Thirtieth Congress, he was chairman of the Committee on Expenditures in the Department of War, although he opposed the then-ongoing Mexican–American War. Crozier also obtained $50,000 in federal funding for navigational improvements to the Tennessee River, which he hoped would eventually connect Knoxville and Chattanooga to the nation's inland waterways. After his second term, Crozier resumed the practice of law in Knoxville, and along with his brother-in-law, J. G. M. Ramsey, championed railroad construction in the region. Crozier supported Whig candidate Winfield Scott during the presidential election of 1852, but after the Whig Party disintegrated in subsequent months, he affiliated himself with the Democratic Party. Crozier supported Democratic presidential candidate James Buchanan in 1856, and campaigned in Knoxville on behalf of Southern Democrat John C. Breckinridge during the presidential election of 1860.
Crozier's defection to the Democratic Party resumed a string of personal attacks from Knoxville Whig editor, William "Parson" Brownlow, which Crozier later claimed drove him from public life. During the presidential campaign of 1860, Crozier and Brownlow attacked one another in speeches, and continued quarrelling via newspaper editorials in 1861 as they stood on opposite sides of the secession debate. Brownlow called Crozier "a corrupt demagogue, a selfish liar, and an unmitigated coward," while Crozier argued that Brownlow had earned his fortune by publishing lies. In December 1861, Crozier's nephew, Confederate district attorney J. C. Ramsey, had Brownlow jailed for treason. When the Union Army occupied Knoxville in September 1863, General Ambrose Burnside chose as his headquarters Crozier's house at the corner of Gay Street and Clinch Avenue. Crozier's extensive personal library made his house the ideal choice for Burnside, an avid reader. During the waning years of the war, Crozier made amends with the city's Unionists. In 1865, Brownlow won a $25,000 judgement against Crozier and two other Confederate leaders, but the decision was eventually annulled.
Later life
After the war, Crozier retired from practice to engage in "literary pursuits." In 1869, he delivered a lecture before the Young Men's Literary Society entitled, "What Studies Most Expand the Human Mind?" In 1883, he helped revive the East Tennessee Historical Society, which he and his brother-in-law, J. G. M. Ramsey, had established in 1834. Crozier died in Knoxville on October 25, 1889, and was interred in Old Gray Cemetery. Following family tradition, his grave was not individually marked. Crozier's daughter, Lizzie Crozier French, led efforts for women's suffrage and coeducation in Tennessee. His son, John Crozier, Jr., was an early aviation pioneer who began building a human-powered flying machine in the 1890s, but was killed in a feud in Grainger County before he could complete it.
