Ferguson's political cast will change after municipal elections are held there next Tuesday, but it's not yet clear how much residents care.

Voter registration is up by about 5 percent in Ferguson since the shooting death last August of Michael Brown and the months of protest that followed. But that's not substantially greater than in the rest of St. Louis County, Mo., despite extensive outreach efforts by the NAACP, student groups and local activists.

That doesn't mean the protests will have no political effect, however. There's an attempt underway to recall Mayor James Knowles. And, putting aside the wave of ousters of top staff at City Hall that followed the Justice Department's damning report of the town's policing, fees and court policies, there are four African-Americans running for three city council seats next week. (None of the incumbents is running.)

That's one more black candidate than Ferguson had previously seen in its entire history. And turnout is bound to be higher than the anemic 13 percent seen in municipal elections two years ago.

"At least more candidates are presenting themselves, which is in and of itself an impact," said Stan Veuger, a resident scholar at the American Enterprise Institute.

There's also an election next Tuesday in Wisconsin, which saw large-scale protests several years ago in response to the abolition of collective bargaining rights for most public employees and again last month over the state's new anti-union law. State Supreme Court Justice Ann Walsh Bradley, one of the court's remaining liberals, is seeking to retain her seat against challenger James Daley.

Veuger is the coauthor of a study that looked at how Tea Party protests affected voter behavior. He and his colleagues found that whether it rained locally during Tea Party protests on April 15, 2009 made a difference in turnout the following year. Rain meant smaller rallies, fewer volunteers and less money raised for political causes.

That may sound a bit outlandish, but Tea Party protests in general clearly had network effects, with activists organizing, building up relationships and eventually working on political campaigns. Not so much for the Occupy movement, which never crafted a coherent policy agenda, let alone got involved in political races.

Protesters march in the rain on the Wisconsin State Capitol against the right-to-work law in February. (FlickrCC/Milwaukee Teachers' Education Association)

Throughout American history, protest movements have sometimes led to increased turnout. Georgetown University historian Michael Kazin points, for instance, to the Populist movement around the dawn of the 20th century, which helped drive election turnout up by nearly 5 percentage points between 1892 and 1896. Turnout that year -- 79.3 percent of the voting-age population -- hasn't been matched since.

Sometimes protests are about a specific cause -- ending a war, raising the minimum wage -- and may not translate into support for a slate of candidates.

Of course, the successful fight for greater enfranchisement of African-Americans led not only to changes in laws but voter behavior as well.

"If you look at what happened after the Voting Rights Act, you had representation for African-Americans in a way you didn't have before," said Rosemary Feurer, a historian at Northern Illinois University. "That was a movement saying it was a political injustice that you couldn't vote."

Some 3 million African-Americans were registered in the South in the decade following passage of the Voting Rights Act in 1965, with nearly 1,200 black officials elected in the region over those years.

But, Feurer notes, opponents of protest movements get mobilized as well. "In the South, the initial campaigns brought out a huge backlash," she said.

In 1968, some Southern whites came out to support the third-party presidential bid of former segregationist Alabama Gov. George Wallace who "may not have cared much about voting in 1964," said Kazin.

Many voters around the country that year may have changed their stances because of protests, with Republican Richard M. Nixon winning on a promise to restore "law and order" amidst the demonstrations and riots of the 1960s, including at the scene of that year's Democratic National Convention in Chicago.

Protesters seem to have triggered a backlash more recently in Wisconsin. Anger over GOP Gov. Scott Walker's labor policies led to large demonstrations at the capitol in 2011 and an attempt to recall him the following year.

That effort failed, with Walker collecting some 200,000 more votes than he had in 2010. Last November, he won again amidst the highest turnout Wisconsin had seen since the 1950s -- even as turnout around the country was at its lowest ebb since World War II.

"Particularly on the Republican side, turnout was higher than it normally is," said Jay Heck, executive director of Common Cause in Wisconsin. "Republicans did what Democrats usually do -- they got people to the polls more effectively than the Democrats did."

If Walker was able to build on the organizational and fundraising base he'd built up as a result of the recall election, the labor unions that had challenged his policies and pushed for his recall had been largely eviscerated.

Last month, Walker signed a right-to-work bill that will weaken unions in the private sector, which triggered a renewed round of protests.

Whether that will make a difference when it comes to next week's judicial election remains to be seen, but Heck is skeptical. The major protests took place four years ago. While Walker remains a polarizing and motivating force for partisans on both sides and has built up a powerful machine, the unions have been greatly weakened.

This year's state Supreme Court race, while expensive and hotly contested, doesn't seem to have the same force as a proxy battle as a similar contest back in 2011.

"If there was a reaction against the protests in Madison, that was much more of a factor during the recall election in 2012," Heck said.