timeline 1850-1890 By AntaneakR Mar 3, 1870 black man vote - 1870 The 15th amendment was passed and black men became able to vote by law Jul 31, 1875 New president - 1875 Andrew Johnson became president after the assassination of Abraham. Apr 30, 1879 How thanksgiving became - 1879 the lady who convinced president Lincoln to make thanksgiving a holiday passed at age 90