what year was back men able to vote?

Answer 1

Check this article.

http://www.ourdocuments.gov/doc.php?flash=true&doc=44

Answer 2

A few black free men in northern states had the right to vote from the early days of the republic. The right to vote by ALL black men was written into the Constitution in 1865-1870 by the Thirteenth, Fourteenth and Fifteeth amendments. Most remained unable or prevented from voting in southern states by poll taxes, intimidation and other means until the Civil Rights Act was passed during the presidency of Lyndon Johnson (1965). Until that happened, southern state filibusters in the Senate and the Ku Klux Klan kept voting rights from being effectively guaranteed to blacks for nearly a century.