The databases you ultimately search will depend heavily on your specific subject focus, but the following generally work for almost any political science-related topic.
Abstracts from the international literature on public affairs, public and social policies, and international relations, 1915-present. Sources are varied and include journals, government reports, and gray literature. Includes articles on many political science topics. (ProQuest)
Rich portal for political facts and figures - directories, encyclopedias, factbooks, almanacs. Includes CQ Almanac, CQ Weekly, and about 30 online reference books on American government and politics.
Combined interface for searching Early American Imprints I & II (1639-1819), American State Papers (1789-1838), and the U.S. Congressional Serial Set (1817-1980).