Distances.

When Thomas Jefferson became president in 1801, he described for the American people the particular blessings they enjoyed. They were "kindly separated by nature and a wide ocean from the exterminating havoc of one quarter of the globe," and they "possessed a chosen country, with room enough for our descendants to the thousandth and thousandth generation." In 1801 the western boundary of this enormous country was on the Mississippi River, while its southern border did not reach the Gulf of Mexico. Most of this territory, however, was still in the hands of Native Americans, and the possibility that they might easily be forced out was remote. For Jefferson the distances and scale of the New World were magnificent, the forests and prairies filled with promise and possibilities. For others, though, the size of the country presented problems. During the Constitutional Convention of 1787, when a delegate suggested that the task...