When first wrote, the USA constitution was produced with some consideration for the future but, the future could not be predicted. At the time of writing and ratification, society was racially segregated and biased by gender. The original constitution didn't promote this behaviour but, the social situation reflected in US politics and it wasn't until three separate amendments came into force, that the new social change was shown. Those three amendments were the fifteenth, nineteenth and twenty-sixth amendments.
In 1870, the fifteenth amendment was ratified. The amendment declared race or colour could not be used as criteria when voting. This took some discriminative factors away from the constitution and therefore, made it more democratic by giving more people a free vote. Women were still being discriminated against and it wasn't until the nineteenth amendment came into force in 1920, that gender biased was removed. Like the fifteenth amendment, the nineteenth amendment removes some of the discrimination of US politics and promotes democracy in the US by giving more people the vote. The twenty-sixth amendment lowered the voting age to 18. This gave more people the vote. Before these three amendments, only those with white skin; were male and over the age of 21 could vote. By passing these amendments, more people were eligible for the vote. Of course, the passing of a constitutional law is a major step forward but, social situation did not improve straight away, it had to develop over time. Still, it can be said that by allowing more people to be eligible for the vote means strengthening the democratic nature of the US constitution.
The US played a big part in the slavery and slaves were still in force when the constitution was written. A big part of democracy is of course a free life and the pursuit of happiness. The thirteenth amendment to the US constitution was ratified in 1865 and abolished all slavery in the United States. Removing slavery from society is a massive step towards making the nation more democratic. Giving more of the US people the right to freedom promotes democracy in the US.
Voting was another issue covered in the twenty-fourth amendment to the constitution, ratified in 1964. This amendment ensured that states could not link the payment of tax with the right to vote. So, if taxes are not paid by a citizen then that citizen must still retain the right to vote. The right to a free vote is a democratic must. This amendment improved democracy in the United States.
Brought into force in 1913 was the 17th amendment to the constitution. No longer could states elect members of the Senate. The passing of this amendment gave the public the right to vote for their elected Senator. Giving more political positions elected status, ensures the public have the choice of those representing them and promotes democracy.
The last seventeen amendments to the constitution have promoted a more democratic constitution by including more people in the US political process and ensuring that the represented are having a free vote for who their representative is.