361. Growth of the Country.--The United States was now three times as large as it was at Jefferson's election. It contained over three million square miles of land. About one-third of this great area was settled. In the sixty years of the century the population had increased even faster than the area had increased. In 1800 there were five and a half million people living in the United States. In 1860 there were over thirty-one million people within its borders. Of these nearly five millions were white immigrants. More than half of these immigrants had come in the last ten years, and they had practically all of them settled in the free states of the North. Of the whole population of thirty-one millions only twelve millions lived in the slave states, and of these more than four millions were negro slaves. [Sidenote: New states. _McMaster_, 365-368.] 362. Change of Political Power.--The control of Congress had now passed into the hands of the free states of the North. The majority of the Representatives had long been from the free states. Now more Senators came from the North than from the South. This was due to the admission of new states. Texas (1845) was the last slave state to be admitted to the Union. Two years later the admission of Wisconsin gave the free states as many votes in the Senate as the slave states had. In 1850 the admission of California gave the free states a majority of two votes in the Senate. This majority was increased to four by the admission of Minnesota in 1858, and to six by the admission of Oregon in 1859. The control of Congress had slipped forever from the grasp of the slave states. [Sidenote: The cities.] [Sidenote: New York.] [Sidenote: Chicago.] 363. The Cities.--The tremendous increase in manufacturing, in farming, and in trading brought about a great increase in foreign commerce. This in turn led to the building up of great cities in the North and the West. These were New York and Chicago; and they grew rapidly because they formed the two ends of the line of communication between the East and the West by the Mohawk Valley (p. 239). New York now contained over eight hundred thousand inhabitants. It had more people within its limits than lived in the whole state of South Carolina. The most rapid growth was seen in the case of Chicago. In 1840 there were only five thousand people in that city; it now contained one hundred and nine thousand inhabitants. Cincinnati and St. Louis, each with one hundred and sixty thousand, were still the largest cities of the West, and St. Louis was the largest city in any slave state. New Orleans, with nearly as many people as St. Louis, was the only large city in the South. [Sidenote: The North and the South.] [Sidenote: Growth of the Northwest.] [Sidenote: Density of population, 1860.]