Chapter 4: Spatial Politics, footnote 15, page 145 Ch4 fn. 15 p. 145 Tags: Pure Citation, Published Letters/Correspondence, Histories and Biographies Van Horne to Purvis, July 14, 1884, Van Horne LB, 6, vol. 2, 901-10 Van Horne to C. J. Brydges, Feb. 23, 1884, Van Horne LB, 4: 856-6, vol. 1. Van Horne to Purvis, Sept. 16, 1885, Van Horne LB, 13: 455-58, vol. 2. Van Horne to Egan, Jan. 6, 1884, Van Horne LB, 4:180-82, vol. 1. Van Horne to C. J. Brydges, July 26, 1883, Van Horne LB, 2 (2):498, vol. 1. John C. Hudson, "The Grain Elevator: An American Invention," ed., Measure of Emptiness (Baltimore: Johns Hopkins Univ. Press, 1992), 92. The classic account of this transformation of nature into commodity is William Cronon, Natures Metropolis: Chicago and the Great West (New York: Norton, 1991), 97-147.