The three ways that amendments made to the U.S in the 1900s changed the voting process are:
1. In first place, the ratified amendment number 17th (submitted in 1912) determined the Senators election thorough popular vote.
2. In second place, the ratified amendment number 19th (submitted in 1919) forbided the refusal of the right to vote due to sex reasons, and from that moment nobody could prohibit to women to vote in the U.S.
3. And finally in third place, the ratified amendment number 24th (submitted in 1962) forbided the revocation of the voting rights owing to a poll tax payment lack or another payment tax absense.