Timeline of states being added to the Union By 10063-The Conqouer 1860 Start of shown area 1861 State of Kansas founded 1863 West Virginia founded 1864 Nevada added 1867 Nebraska added 1876 Colorado added 1889 North Dakota added 1889 Washington 1889 South Dakota added 1889 Montana added 1890 Idaho added 1890 Wyoming added 1896 Utah added 1900 End of shown area