How did the 14th Amendment change the relationship between the national government and the states?

 In 1866, Republicans proposed the 14th Amendment to the U.S. Constitution, which was ratified in 1868. This amendment is among the most important provisions ever added to the Constitution, and has powerfully shaped the nation's constitutional history since 1868. The 14th Amendment, which was written to protect black Southerners, defines national citizenship. It declares that:

"All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No state shall make any law which shall abridge the privileges and immunities of citizens of the Unites States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws."

The 14th Amendment provides that the federal government will guarantee citizens' rights, and that it will protect them against state laws that would deprive them of freedoms or rights. This amendment decisively tilted the balance of power in the U.S. away from the separate states toward the national government.

Additionally, the 14th Amendment spelled out the terms according to which former Confederate states could regain representation in Congress. It declared that the representation of these states would be reduced as long as black men remained unable to vote. (The amendment specifically mentions "male" voters--the first time the Constitution made explicit reference to sex.) Many women's rights advocates were disappointed by this provision of the amendment. It also made former Confederate officials ineligible to serve in Congress, unless Congress, by a two-thirds vote declared them once again to be loyal Americans. Finally the amendment guaranteed that the U.S. government would pay the debts it had incurred during the war, but would not be responsible for the debts of the Confederacy.