If you haven't already seen Selma, the new movie about Martin Luther King, Jr. and the fight for voting rights, do it tonight or tomorrow.
It's a great film - one of the best I've seen in a long time - and it does a great job of showing why all successful social movements start from the bottom up.
But what's really amazing about Selma is how relevant it is. Nearly 50 years after the events depicted in the film, the right to vote is under threat once again. But this time it's Republicans, not Southern Democrats, who are waging war on democracy.
During the Jim Crow era, it was pretty much impossible for black people to vote. While the Constitution banned voter discrimination based on race, Southern states got around this ban by using tricks and tests to keep African-Americans way from the polls.
These weren't fair tests, either - they were designed to make people fail.
In one scene in Selma, for example, a white official rejects the voting application of a black woman played by Oprah Winfrey because she can't name every single county judge in the state of Alabama.
That's the kind of daily humiliation black people in the South had to deal with until the Reverend Dr. Martin Luther King Jr. and other activists forced the hand of President Lyndon Johnson and he signed into law the Voting Rights Act of 1965.
But now, 50 years later, people of color are experiencing the nightmare of the Jim Crow era all over again.
That's because the Republican Party has declared all-out war on democracy.
Since the 2010 elections, 22 states, almost all controlled by Republicans, have passed laws restricting the right to vote.
While not as blatant as literacy tests, these laws - and let's call them voter suppression laws, because that's what they really are - all have one thing in common: they make it harder for Americans, especially African-Americans, to do what every citizen of a democracy is entitled to do - go to the polls and choose who they want to run their government.
The most obvious example of the GOP's new war on voting is voter ID suppression laws that require people to bring photo identification with them to the polls. Republicans say they're about stopping voter fraud, but since voter fraud doesn't actually exist, that's just cover for their real purpose: stopping black people and even poor or urban whites, who disproportionately lack photo IDs, from voting.
And believe me, these voter ID suppression laws work just as Republicans intended for them to work. A recent study by the Government Accountability office found that they had a real effect by reducing black turnout during the 2012 elections, just as their Republican sponsors hoped and planned.
But voter ID suppression laws are just the tip of the iceberg when it comes to the Republican Party's all-out assault on voting rights.
States like North Carolina and Ohio, for example, have cut back early voting and voting on the Sunday before Election Day, both of which are very popular in the black community.
Republican Kansas Secretary of State Kris Kobach, meanwhile, has helped officials in 27 states kick millions of people, including many African-Americans, off the voting rolls by getting them to use a program called Interstate Crosscheck that numerous reporters have shown to be nothing more than cover for a nationwide voter suppression scheme.
Until 2013, the federal government had the power to block the most extreme of these state-based voter suppression tactics, but in June of that year the Supreme Court gutted the Voting Rights Act, and basically gave right-wing politicians free reign to block the vote in whatever way they see fit.
Oh, and as if this wasn't all bad enough, Republicans have also so gerrymandered our congressional districts that in many cases it doesn't even matter whether you vote or not.
On this Martin Luther King Day, let's celebrate how far we've come since activists marched from Selma to Montgomery to demand the right to vote.
But let's also take the time to realize how much hasn't changed since 1960s, and let's call out Republicans for trying to take us backwards to the dark days of the Jim Crow era.
In our democracy, the right to vote is precious, but constant vigilance and a broad base of voters are the necessary preconditions for a functioning republic.
That was true in 1965, and it's just as true now.