adding eras By Pjohnson16 Period: 1776 to 1860 Early American History Period: 1860 to 1877 Civil War/Reconstruction Period: 1877 to 1900 The Gilded Age Period: 1890 to 1920 The Progressive Era Period: 1898 to 1910 Imperialism Period: 1914 to 1918 World War I