If you know a website that is not listed here, please leave a comment.
The Library of Congress’ American Memory Project maintains a collection of over 8,000 documents on The Chinese in California, 1850-1925.
1868-1883: Cartoons of Thomas Nast on Chinese Immigration to the U.S.
The California Digital Library provides two resources on Chinese immigrants: the Online Archive of California, U.C. Berkeley, has a Guide to the Chinese in California Virtual Collection, mostly from the turn of the 20th Century. Calisphere’s Asian American Cultures collection includes materials on the Chinese Exclusion Act, 1882, Business, Children, the Chung Sai Yat Po Newspaper Collection (1900-1904), Opera & Theater, Social Conditions & Customs, and Westward Expansion.
1917-1932: The Sidney D. Gamble Photograph Collection at Duke University.
1912-1962: Cartoons of David Low on China in the British Cartoon Archive, University of Kent.
1918: Chinese Laborers on the Western Front in The War Illustrated Archives.
1920-1950: The Tibet Album: British Photography in Central Tibet 1920-1950 from the Arts and Humanities Research Council.
1924: The Bucklin China Archive at Duke University.
The Rev. Claude L. Pickens, Jr. Collection on Muslims in China at Harvard University.
1933-1946: The Hedda Morrison Photographs of China at Harvard University.
1933-1974: Chinese Public Health Posters from the National Institutes of Health.
1937-present: Stefan Landsberger’s Chinese Propaganda Poster Page is the most well known and comprehensive English source on the subject. Also available at Chineseposters.net.
1947-1954: Chinese Pamphlets at the Center for Research Libraries. Donated by U.S. journalist and OSS agent Edward Hunter.
1949-present: China.com’s Tuku historical archive is full of all sorts of propaganda material in its “Red Memories” collection. Not the most organized of sites, but full of surprising images from sources ranging from Xinhua to Life Magazine and Getty Photos, of things like the unfortunately named Taoist humanitarian Red Swastika Society of the 1920s, the reinstatement of the university entrance exam in 1978, and the Belgrade bombing protests. There are also photos of ephemera like 1948 Nationalist identity documents and Time magazine covers featuring China.
1963-1979: Picturing Power: Posters of the Cultural Revolution is an online exhibition of propaganda posters that began at Indiana University.
1981: Chineast: Ein China-Blog Aus Shanghai has scanned tourist photographs of Shanghai and Beijing.
Historical Photographs of China brought by the University of Bristol, University of Lincoln, and Institut d’Asia Orientale.
The New York Public Library Digital Collections (search for China, Chinese, etc.)
Images of China OR Chinese on Google’s hosted Life Magazine Archive.
A Visual Sourcebook of Chinese Civilization from the University of Washington.
The new World Digital Library has images, papers and maps on China and East Asia.
The Flickr collection China Postcard has a number of 20th century images and ephemera, including postcards and maps.
The Virtual Shanghai collection at the IAO – Institut Universitaire de France curated by Christian Henriot.