formed by the Mississippi Valley, an agricultural and pastoral region; a plateau supported by the Rocky and Cascade ranges, a metalliferous region; and a territory with the valley of the Sacramento, which slopes to the Pacific, of varied resources.  The great rivers are in the Mississippi Valley, as also the two largest lakes, the Michigan and Great Salt Lake, though there are important rivers both for navigation and water-power on the Atlantic and Pacific slopes.  The climate is of every variety, from sub-arctic to sub-tropic, with extremes both as regards temperature and moisture, in consequence of which the vegetation is varied.  The mineral wealth is immense, and includes, besides large beds of coal, all the useful metals.  The industries, too, are manifold, and embrace manufactures of all kinds, with agriculture, grazing, mining, and fishing, while commerce is prosecuted with an activity that defies all rivalry, the facilities in railway and waterway being such as no other country can boast of, for there are over 182,000 miles of railway, not to mention street railways and traction lines, with telegraphic and telephonic communication.  The population is mostly of British and German descent, with eight million negroes, who are all English-spoken.  The Government is a federal republic of 45 States; the legislature consists of two Houses—­a Senate representing the States, each one sending two members, and a House of Representatives representing the people, every citizen over 21 having a vote, and every 170,000 voters having a representative—­the head of the Government being the President, elected for a term of four years, and commander-in-chief of both army and navy.  Religious equality prevails through all the States, though the Protestant section of the Church is in the ascendant, and education is free and general, though backward in some of the former slave-holding States, the cost being met by State or local funds, supplemented by the Federal Government.

UNITED STATES, PRESIDENTS OF, George Washington (1789-1797); John Adams (1797-1801); Thomas Jefferson (1801-1809); James Maddison (1809-1817); James Munroe (1817-1825); John Quincy Adams (1825-1829); Andrew Jackson (1829-1837); Martin Van Buren (1837-1841); John Tyler (1841-1845); John K. Polk (1845-1849); Zachary Taylor (1849-1850); Millard Fillmore (1850-1853); Franklin Pierce (1853-1857); James Buchanan (1857-1861); Abraham Lincoln (1861-1865); Andrew Johnson (1865-1869); Ulysses D. Grant (1869-1877); Rutherford B. Hayes (1877-1881); James A. Garfield (1881); Chester A. Arthur (1881-1885); Grover Cleveland (1885-1889); Benjamin Harrison (1889-1893); Grover Cleveland (1893-1897); William McKinley (1897-1901); Theodore Roosevelt (1901).

UNITIES, THREE, name given to the rule laid down by Aristotle that a tragedy should be limited to one subject, to one place, and a single day.

UNIVERSALISTS, a body of Christians who profess to believe in the final restoration of all the fallen, angels as well as men; a body chiefly of American growth, having an ecclesiastical organisation, and embracing a membership of 40,000; there are many of them Unitarians, and all are more or less Pelagian in their views of sin.