The 14th Amendment (1868) guaranteed African Americans citizenship rights and promised that the federal government would enforce “equal protection of the laws.” The 15th Amendment (1870) stated that no one could be denied the right to vote based on “race, color or previous condition of servitude.”
They allowed Maine to enter the Union as a slave state AND Maine as a free state. It was more to help balance things out because they did not want to be unfair I guess. They wanted it to be equal.