The more "barriers" the lower the turnout.
In Belgium voting is obligatory ...
Australia too. Sometimes I wish we'd do the same.
I'm glad the US is a democracy (technically a Republic, with a representative democracy). Our system of electing presidents is pretty strange though.
As you have probably heard, we have something called the 'electoral college' -- which, I must add, is only used for the PRESIDENTIAL election, not other elections. Each state is allowed a certain number of "electors" - and in the end, it is THOSE VOTES ALONE which determine the winner. The number of electors for a given state is the same as the number of congressmen that state has (2 Senators, plus a number of Representatives based on population).
Each state is permitted to devise their own method of choosing the electors, but the federal government decides how many each state gets and when the electors must vote (Nov 2, right now.)
All states but 2 (Maine and Nebraska) do it the same way: whoever wins the popular vote for the state wins ALL the electoral votes. Hence, in a 2-candidate race, up to 49.999999% of the populace of a given state may have NO representation in the electoral vote.
The WAY that this is accomplished is even more twisted: each CANDIDATE has his own panel of loyal potential electors, and the popular vote decides which PANEL of electors gets to actually vote. So, in a situation where technically NO actual flesh-and-blood electors are needed (since they don't actually get to make any individual choices when the time comes) we have one complete set per candidate!
Maine and Nebraska do it more sensibly: the 2 "senator" electors vote with the statewide popular majority, and the "representative" electors vote with the popular majority in their respective congressional districts.
This system leaves open the possibility of a candidate winning the election while losing the popular vote - which of course, Bush did in 2000. He is only the 3rd US President to win that way.
Many people, myself included, would like to see this system eliminated - let the nation-wide popular vote decide the winner. But to do that would require a constitutional amendment, which requires a 2/3 majority vote of both houses of congress, and then approval by 3/4 of all states' legislatures -- *extremely* difficult to achieve.