Identify and explain one formal change that has made the constitution more democratic over time.

Formal changes made to the Constitution are called amendments. One amendment that has made the constitution more democratic, meaning giving more power to the general public rather than a select few, is the 19th Amendment. 

The 19th Amendment granted suffrage (the right to vote) to women in 1919. This meant that half the population of the United States was not previously guaranteed the right to vote (the actual percentage was much greater when we consider slavery and other obstacles to suffrage that have existed).

Guaranteeing the right to vote to women made the country much more democratic, because a much larger percentage of the population was enabled to directly participate in the election of public officials.