=Iowa and Minnesota.=--To the southwest of Wisconsin beyond the Mississippi, where the tall grass of the prairies waved like the sea, farmers from New England, New York, and Ohio had prepared Iowa for statehood. A tide of immigration that might have flowed into Missouri went northward; for freemen, unaccustomed to slavery and slave markets, preferred the open country above the compromise line. With incredible swiftness, they spread farms westward from the Mississippi. With Yankee ingenuity they turned to trading on the river, building before 1836 three prosperous centers of traffic: Dubuque, Davenport, and Burlington. True to their old traditions, they founded colleges and academies that religion and learning might be cherished on the frontier as in the states from which they came. Prepared for self-government, the Iowans laid siege to the door of Congress and were admitted to the union in 1846. Above Iowa, on the Mississippi, lay the territory of Minnesota--the home of the Dakotas, the Ojibways, and the Sioux. Like Michigan and Wisconsin, it had been explored early by the French scouts, and the first white settlement was the little French village of Mendota. To the people of the United States, the resources of the country were first revealed by the historic journey of Zebulon Pike in 1805 and by American fur traders who were quick to take advantage of the opportunity to ply their arts of hunting and bartering in fresh fields. In 1839 an American settlement was planted at Marina on the St. Croix, the outpost of advancing civilization. Within twenty years, the territory, boasting a population of 150,000, asked for admission to the union. In 1858 the plea was granted and Minnesota showed her gratitude three years later by being first among the states to offer troops to Lincoln in the hour of peril. ON TO THE PACIFIC--TEXAS AND THE MEXICAN WAR