Parkland, Fla. • After Manuel and Patricia Oliver lost their son in the Marjory Stoneman Douglas High School shooting, they assumed their neighbors would be sympathetic. So when they protested gun violence last summer by staging a “die-in” at the local Publix grocery store, they were shocked by the reaction.

Gun rights activists and some shoppers taunted and mocked them. One stepped on Patricia's hand, saying, "I'm sorry for your loss," she recalled. Another man swore at Manuel while screaming his support for the National Rifle Association.

"We were shocked there were all of these people against us, in a very rude way," said Manuel Oliver, who advocates for gun control in memory of their 17-year-old son, Joaquin. "And it was at that moment, I realized I need to be ready to find out a lot about where I live" on Election Day.

The shooting, which left 17 students and staff members dead last year, sparked a nationwide movement of marches, student walkouts and a massive voter registration campaign to demand gun control. More than 100,000 supporters converged on downtown Washington a year ago for a rally that became a defining symbol of the students' determination to upend American politics.

But the movement has had relatively little effect on voters here, who made a three-point shift toward the Democratic candidate between the 2016 presidential election and the 2018 gubernatorial election, when compared with Florida voters overall.

A Washington Post analysis of voting results shows a similar trend following other recent, large mass shootings: a modest swing toward Democratic candidates, who often champion gun control laws, with Parkland's three-point shift at the median.

"You would think, indeed, because everyone in these places knows people who know people affected by this, that that personal experience would magnify the impact," said Robert Spitzer, who has written five books on the politics of gun control. "But my general assumption is those communities' larger focus generally really isn't about politics, and it really does not profoundly change local politics."

The Post’s review examined communities that experienced seven of the deadliest mass shootings since Newtown, Connecticut, including Orlando; Las Vegas; Pittsburgh; San Bernardino, Calif. and Sutherland Springs, Texas.

The analysis used results in the first presidential or gubernatorial election after each attack compared with the one immediately preceding. In most cases, the changes were only slightly different from the trends across the state, but they varied widely.

After 26 children and staff members were killed at Sandy Hook Elementary School in 2012, voters in Newtown shifted two points in favor of the incumbent Democratic governor in 2014, a year when the state moved decisively to the right compared with the previous presidential election. In San Bernardino, where 14 people were killed at a county government office in 2015, voters made a 17-point shift in favor of the 2016 Democratic presidential candidate, while the state swung to the left by less than 10 points.

In a separate study published by the British Journal of Political Science in February, researchers "failed to find any significant or substantively meaningful" overall effect of mass shootings on political views regarding gun control laws. However, the results showed local residents' opinions became more polarized.

"There is no aggregate movement among everyone," said Brian Schaffner, a political science professor at Tufts University and one of the study's authors. "But we saw some evidence Republicans become more conservative and Democrats become more liberal."

In Parkland, where Stoneman Douglas High School students organized a nationwide March for Our Lives campaign and gun-control advocates spent millions of dollars on statewide elections, Democrat Andrew Gillum carried five of Parkland's six precincts in Florida's gubernatorial election.

But Republican challenger Ron DeSantis, who campaigned against stricter gun laws, carried one Parkland precinct with 54 percent of the vote, roughly matching the level of support President Donald Trump received in that precinct in 2016.

Florida elected DeSantis and sent Republican Gov. Rick Scott to the U.S. Senate, strengthening the GOP Senate majority, while dimming hopes for federal action on gun laws.

"I kept hearing before the election that Democrats were going to take this race or that race in Florida, and I just kept telling myself, 'I am not seeing it,' " said Kristin Jacobs, a Florida state representative who represents Parkland.

Parents of the Parkland shooting victims also remain split on gun control. They agreed to largely avoid discussing politics when they meet as a group for emotional support.

"I'm not interested in having that discussion," said Max Schachter, who lost his 14-year-old son, Alex, in the shooting and now pushes for school safety improvements. "I work with Republicans and Democrats to make schools safer than they were when my son was murdered."

Several parents became advocates for gun control, including the Olivers, who travel nationwide with their artwork promoting tougher gun laws. But other parents have been outspoken against new gun-control measures, focusing on what they view as the systemic failure in the Feb. 14, 2018, attack.

"If it was just the gun, I would say, ‘OK, it’s the gun’s fault,’ " said Andrew Pollack, whose 18-year-old daughter, Meadow, was killed in the massacre. “But I did an investigation into every facet of how my daughter was murdered. There are multiple failures — from the sheriff, to the mental health system to the monitors at the school. How can you say it’s the gun’s fault?”

The effort to launch a gun-control movement here did yield some results. About 250 Parkland residents between ages 18 and 21 registered to vote after the shooting, ahead of Election Day, and about 57 percent of them voted — compared with a 47 percent turnout statewide among new registrants in that age group, according to an analysis by Daniel A. Smith, chairman of the political science department at the University of Florida.

In the 18-to-29 age group, Democrats in Parkland turned out in larger numbers, with 54 percent casting ballots, compared with 42 percent of Republicans and 35 percent of unaffiliated voters, said Smith, who analyzed Florida's open-source voter file.

In Newtown, voters shifted two points to the left between the 2012 presidential election and the 2014 governor's race. But other comparisons show a more robust advantage for Democrats, including a 20-point swing toward then- Gov. Dannel Malloy, a Democrat, in his bid for reelection in 2014 compared with four years earlier.

After the Sandy Hook shooting, Malloy successfully pushed for major changes to Connecticut gun laws, including universal background checks and a stronger assault-weapons ban.

But since that election, Newtown has remained divided politically.

In November, Newtown voters split partisan loyalties in statewide races, supporting incumbent Democratic Sen.Chris Murphy, a gun-control proponent, while also narrowly backing Republican Bob Stefanowski in the Connecticut governor's race. Stefanowski was endorsed by the NRA.

Stefanowski's anti-tax message resonated with suburban Connecticut voters, said Gary L. Rose, a political science professor at Sacred Heart University in Fairfield, Connecticut.

Gun-control advocates caution that the results of presidential and statewide contests can offer a limited view of the true effect a mass shooting has on the politics of a community. Often, they say, the debate over gun control plays out in a more visible way in races for state legislative or congressional elections.

In one Newtown-area state legislative district, voters last year ousted GOP incumbent Will Duff in a race that partially hinged on his vote opposing a statewide ban on bump stocks, devices that allow a gun to fire more rapidly.

Nationwide, advocacy group Everytown for Gun Safety said that more than 1,000 candidates who supported gun-control measures were elected last year, including 171 congressional candidates, 15 governors and 12 state attorneys general.

Monte Frank, a Newtown attorney who became a gun-control activist after the Sandy Hook tragedy, said the gains Democrats made last year show the building potency of the movement. Now, he said, voters in Newtown and elsewhere consider a candidate's stance on firearms laws even if it they don't always rank it as a top concern.

"There is no question in my mind, in the six years since Sandy Hook, that gun violence has become a much larger factor in how people vote, especially in Newtown," Frank said. "But there are still others that still consider it as part of the overall package, and just one factor of many."

Only one of the seven communities in The Post analysis became more Republican after a mass shooting: Sutherland Springs.

After a gunman killed 26 people — including an unborn baby — at a Baptist church there in 2017, voters in that precinct shifted six points in favor of Republican Texas gubernatorial candidate Greg Abbott, who won the election.

Many residents in Sutherland Springs dismissed questions about whether easy access to guns played a role in the massacre, noting that an armed man near the church confronted the shooter and probably saved lives.

"The ideology that came out of Parkland just wouldn't ever remotely grow legs down here in South Texas, I don't believe," Frank Pomeroy, the pastor of the church, said in an interview on "Here & Now" on WBUR radio last year. Pomeroy's 14-year-old daughter was killed in the shooting.

The Post's analysis did not include the 2013 shooting at the Navy Yard in Washington, D.C., which doesn't have gubernatorial elections. Twelve people were killed in that attack.

Voters in Allegheny County, Pennsylvania, which includes Pittsburgh and its suburbs, and Clark County Nevada, which includes Las Vegas and it suburbs, largely conformed to the broader statewide shifts in their respective states. In Las Vegas, 58 people were killed. Eleven people died in Pittsburgh.

In some places, it's difficult to determine the impact that gun violence has had on the electorate because the community's politics were already changing. In Orange County, Florida, where 49 people were killed at a nightclub in Orlando in June 2016, a surging Latino population helped feed a 13-point shift toward the Democrats in November 2016 compared with the 2014 gubernatorial election. Statewide, Florida moved just 1 percent to the left during the period.

Ken Toltz, a Colorado gun-control activist, knows how complex residents' views about guns can be, even in the aftermath of a mass shooting.

In 2000, a year after the Columbine High School shooting in suburban Denver, a Democrat challenged then-Rep. Tom Tancredo, a Republican, in the congressional district where the school was located. He lost by 12 points.

After watching Colorado remain a right-of-center state for two decades, Toltz believes the politics of the gun debate are shifting because of the activism of the Parkland students.

In November, voters in the congressional district that includes Columbine and Aurora, where a gunman killed 12 people in a movie theater in 2012, ousted Republican Mike Coffman, who had been endorsed by the NRA, from Congress.

“When I look at the big picture, I see a slew of people newly active politically,” Toltz said. “And candidates themselves are campaigning on it instead of running away from it.”