16th Amendment - Granted the Federal government the ability to create a Federal income Tax (some disagree that this was properly ratified)
17th Amendment - sets up the states for the direct general election of Senators instead of being elected by STATE legislatures. (This weakened States Rights)
19th Amendment - Women granted voting rights
20th Amendment -moved the beginning and ending of the terms of the president and vice president from March 4 to January 20
22st Amendment - Limits the number of terms to 2 for the President.
23rd Amendment - Gives the right to vote to DC
24th Amendment - Prohibits Poll Tax
25th Amendment- clarifies that the vice president becomes president if the president dies, resigns, or is removed from office, and establishes how a vacancy in the office of the vice president can be filled.
26th Amendment - prohibits the states and the federal government from using age as a reason for denying the right to vote to citizens of the United States who are at least eighteen years old.
27th Amendment - prohibits any law that increases or decreases the salary of members of Congress from taking effect until the start of the next set of terms of office for representatives.
I think everyone should be born a US National. They get all the rights or a citizen except voting in federal elections, holding certain offices, and performing certain government functions (like issuing passports or enhanced drivers licenses). American Samoans have this classification.
Everyone should be required to take our current citizenship test to become a citizen and get the right to vote. I don't think it's terribly difficult, but most Americans couldn't pass it. And it forces you to learn about civics and some history subjects.