When the time came at which Congress could abolish the slave trade, a law was promptly passed, after considerable angry debate as to its terms, prohibiting the slave trade after December 31, 1807. In fact, it was necessary to even effect a compromise on this subject on the point as to what should be done with any slaves that might be imported contrary to the law; and it was decided that they should belong neither to the importer nor any purchaser, but should be subject to the regulations of the State in which they might be brought. As far as it restrained the South, the law abolishing the slave trade proved to be more of a dead letter than the Fugitive Slave Law did in the North, because the slave trade was carried on with more or less openness until the Civil War, it being estimated that about fifteen thousand slaves were brought into the country annually. The abolition of the slave trade caused several of the border States to devote their attention to slave breeding, which, with the increased demand and the large advance in prices, became a profitable industry in Virginia, Maryland and Kentucky. The acquisition in 1803 of the Louisiana Territory, the wonderful and romantic exploration of it by Lewis and Clark in 1804-5, the closing of the Indian Wars and the second war with England, and hard times in the East, caused that tremendous rush of population to the West, which resulted in the admission of so many new States prior to 1820, and opened anew the slavery question. Vermont, admitted in 1791, Kentucky 1792, Tennessee 1796, Ohio 1803, Louisiana 1812, Indiana 1816, Mississippi 1817, Illinois 1818, and Alabama 1819, had raised the number of States to twenty-two; eleven free and eleven slave; the early custom of admitting a free and slave State together having been strictly followed. The admission of these States effectively partitioned all of the territory east of the Mississippi between Freedom and Slavery, with the exception of the Michigan Territory (subsequently divided into Michigan and Wisconsin), and the new Territory of Florida, purchased from Spain in 1819. West of the Mississippi only one State had been admitted, and the rest of the land was known as the Missouri Territory. The tide of population passing down the Ohio, or through the States, had crossed the Mississippi into the Missouri country, and Missouri, in 1818, petitioned Congress for permission to form a Constitution and enter the Union. Nothing was said about slavery, but it was known that the great majority of the Missouri settlers were slave owners or sympathizers, as those who held anti-slavery opinions were content to remain in the States formed out of the Northwest Territory, and it was therefore certain that Missouri would be a slave State. [Illustration: The Capitol, Washington, D. C.]