After the Camp Jackson episode the wavering took a firm stand on one side or the other. But it soon became evident that the city was overwhelmingly Unionist in sentiment. Lynch's "slave pen," a place where adult slaves had been sold at auction, was closed, and the slave pen where children were sold was soon trans formed into a military prison. Eminent citizens hoped that the warring factions in the State might be brought into agreement by a. conference of the leaders. On June i r Gov. Jackson and Gen. Sterling Price met Blair and Lyon in a conference at the Planters' hotel, but no agreement was reached. The governor hastened to Jefferson City, issued a call for 50,00o troops, and then evacuated the capital.
Throughout the Civil War St. Louis remained a Unionist strong hold. There Gen. John C. Fremont, in command of the western department, established his headquarters, and from there Gen. Hallock directed movements in the Mississippi valley. Thousands of troops were encamped in and about the city. For many months St. Louis was under martial law; thousands of prisoners of war, and some 40,000 refugees were cared for during the war. St. Louis was the headquarters of the Western Sanitary commission which had charge of much of the war relief work.
For a quarter of a century after the Civil War the city was the centre of a remarkable philosophic and cultural movement. Its inspirer was Henry Conrad Brokmeyer (1826-1906), who later became prominent in State politics and was lieutenant governor of Missouri in 1876-1880. Brokmeyer, a Prussian from Minden, came to St. Louis in 1856. He made a translation of Hegel's Logic, but it was never published. Brok meyer attracted William T. Harris, a brilliant graduate of Yale university, who taught in the St. Louis schools during 1858-67 and was superintendent of schools during 1867-80. Brokmeyer and Harris gathered about them a group of idealistic thinkers and formed a philosophical society which became the sponsor of The Journal of Speculative Philosophy (1867-93), the first periodical of the sort in English. For many years Harris, its editor, was the foremost exponent of Hegelian philosophy in the United States.
Af ter the Civil War St. Louis grew with unusual rapidity ; by 1870 the population was 310,864. In ten years it had almost doubled; St. Louis had become the principal distribution point for the Mississippi valley. But it soon found its supremacy challenged by Chicago, when the railroads made Chicago the terminal for lines to the Pacific coast. After 1870 the Mississippi and Ohio rivers gradually lost their importance as highways and the railroads became the great carriers of inter state commerce.
Since 1870 the history of St. Louis has been mainly economic. It has retained its prominence as a wholesale centre and has also become one of the greatest manufacturing cities in the world.
In 1898 a site on the western outskirts of the city was selected for an exposition to celebrate the 1 ooth anniversary of the purchase of Louisiana from France. The grounds covered 1,240 ac., of which 25o were under roof. The total cost, apart from individual exhibitions, was about $42,500,000, of which the National Government con tributed $5,000,000 and the city and citizens of St. Louis $10, 000,000. The exposition was opened to the public in 1904. During the seven months of its existence, 12,804,616 paid admissions were collected, and total admissions were 19,694,855. When the ex position closed the company had a favourable balance of about $1,000,000. Two permanent buildings remain from it, the Jeffer son Memorial, the home of the Missouri Historical Society, and the Art building.
Since 1904 Saint Louis' progress has been steady. In 1908 a free railroad and traffic bridge was opened and in 1914 the present city charter was adopted. In 1919 the municipal opera was inaugurated and extensive plans for civic im provement were made possible by a large bond issue in 1923.
There was a serious flood and a cyclone during 1927. In 1933 the city elected its first Democratic mayor in twenty-four years. In 1934 a Federal building was begun and 1935 saw the passage of a state sales tax and the dedication of a new convention hall.