Let us keep a place where real research men can find quiet, keen intellectual stimulation, freedom from any outside distraction." This was the response of a prominent North American naturalist opposed to a 1924 proposal to build facilities for women at the Barro Colorado Island Biological Laboratory in Panama. In the first decades of the twentieth-century, in the aftermath of the Spanish-American War and as the United States built the Panama Canal, the American tropics became a major focus for North American politics and natural history, with government funding and logistical support from the military for scientific expeditions. As the North American western frontier closed, the New World tropics—or Neotropics—assumed the role that the West had played for an earlier generation of nineteenth-century explorers. In a post-Darwinian world, a field trip to the tropics with its rich biodiversity had become a rite of passage and a route to fame for young North American naturalists. And in the decades during and after the successful campaign for women's suffrage in the United States, tensions between men and women ran high, in the home, at the ballot box, and at the field station.