Acknowledgment is due the publishers for their kind permission to print quotations or reproduce illustrations from the following works:

Allan G. Bogue, Money at Interest: The Farm Mortgage on the Middle Border, copyright © 1955. Ithaca, N. Y.: Cornell University Press.

2.1Real Gross National Product per Capita and Implicit Price Index

2.2Population and Labor Force

2.3Material Capital Stock

2.4Miles of Main Railroad Track

2.5Costs of Education

2.6Percentage Distribution of Commodity Output

2.1Arrivals Minus Departures, All Alien Passengers

2.2Spatial Distribution of Population, 1870

2.3Spatial Distribution of Population, 1880

2.4Spatial Distribution of Population, 1890

2.5Spatial Distribution of Population, 1900

2.6Spatial Distribution of Population, 1910

[O]bservations . . . are always interpretations of the facts observed . . . [and] they are interpretations in the light of theories.

KARL R. POPPER

Some get an infinitely better and easier living, but others find it hard to get a living at all.

HENRY GEORGE

[T]he simplifications of an analytical method furnish a powerful tool for understanding some of the fundamental controlling interrelationships in historical change. That such a technique makes explicit those daydreams on which our judgment of what is important in history are, always have been, and must be based is no doubt an embarrassment; but, to those who have stomach for this sort of game, it can become the road to a wider and truer understanding.