Please see Westward Expansion tab
Alaska Historical Society: Primary Source Documents
Library of Congress: Alaska : message from the President of the United States in relation to the transfer of territory from Russia to the United States.
Library of Congress: Treaty concerning the cession of the Russian possessions in North America by His Majesty the emperor of all the Russias to the United States of America.
National Archives: Check for the Purchase of Alaska (1868)
University of Hawai'i at Manoa Library: The Annexation Of Hawaii: A Collection Of Documents
Duke University, Special Collections Library: George Percival Scriven: An American in Bohol, The Philippines, 1899-1901 (diary excerpts) and
History Matters: Manifest Destiny, Continued: McKinley Defends U.S. Expansionism
The Kipling Society: "The White Man's Burden" (The United States and the Philippine Islands), 1899 poem by Rudyard Kipling
History Matters: “The Poor Man’s Burden”: Labor Lampoons Kipling (satirical poem by George McNeill in response to Kipling's "The White Man's Burden", published 1899)
University of Hawaii: Philippine Revolutionary Papers, 1898-1900
U.S. Dept. of State: Office of the Historian: search results for Philippines (limited to dates 1/1/1890--12/31/1914
History Matters: Bitter Harvest: A Puerto Rican Farmer Laments U.S. Control of the Island (1899 interview of Severo Tulier by Henry K. Carroll, the Special Commissioner for the United States to Puerto Rico)
Digital Library of America: The Panama Canal
Digital Public Library of America: American Imperialism: The Spanish-American War Source Set
Library of Congress: The Spanish-American War in Motion Pictures