One of the necessary elements of democratic government is universal suffrage, essentially providing the right to vote to every citizen of the nation. Even if a nation-state has regular, fair elections to determine its political leaders and accords its citizens the right to free expression, if it restricts the right of certain individuals to participate in the political process by not allowing them to vote, it can not be considered a democracy in the modern sense. In fact, many nations, including the United States, have adopted other elements of democratic rule, such as competitive elections, before ensuring that the entire population had access to the ballot.

Because voting rights are intrinsically tied to the concept of democracy, much of the theoretical basis for explaining the expansion of voting rights is tied to the work on the development of democracy in general. A popular theory is that...