The bullet that former president Donald Trump said grazed his right ear was one of dozens aimed at U.S. presidents, presidential candidates and other prominent elected officials over nearly 200 years.

But Saturday’s assassination attempt, while shocking, is unlikely to have significant political or economic reverberations given the makeup of the American democratic system and the fact that it didn’t involve an incumbent head of state, researchers say.

“While it has been an event that has shaken up the nation, it’s not likely to have a great impact on either the outcome of the election or the U.S. economy,” said Zaryab Iqbal, a professor of political science and Jewish studies at Penn State University in University Park, Pennsylvania.

That’s evident, she said, in the fact that both the NASDAQ and Dow Jones Industrial Average continued to rise Monday as they have over the last few weeks.

“That tells you that people recognize that this is not an event that’s going to have a lasting impact on the political or economic well-being of the nation,” Iqbal said. “At best, an event like this temporarily derails focus on key issues. But ideally, it does not impact the ultimate outcome.”

At least 15 assassination attempts or assassinations have occurred in the U.S. since 1835. Four presidents have been assassinated, as were two presidential candidates. Meanwhile, numerous other attempts have been made on the lives of current and former presidents and other elected officials.

Christopher Zorn, a colleague of Iqbal's at Penn State, agrees that Saturday's assassination attempt is unlikely to produce additional violence or instability.

"I think the effect will be mixed for both parties," Zorn, a professor of political science and sociology, told USA TODAY via email. "While the event may lead to some additional support for former President Trump, it also took attention away from the intense scrutiny on President Biden and the Democratic party in the last week or two. The result may thus be to help both candidates in different ways, with the possible overall effect being relatively slight."

In a 2008 global study, Iqbal and Zorn found that the effects of assassinations on political instability were greatest in systems without formal, regulated processes of passing down leadership roles.

“The pernicious effects of an assassination are exacerbated in states that lack a regularized means of leadership succession, and are muted by the presence of such institutions,” they wrote.

In countries that lack regulated democratic institutions in place, assassination of a head of state is viewed as the only way to voice grievances and bring about political change, they found.

By contrast, in political systems with fair, regular elections, dissatisfied factions are often content to wait things out until the next voting cycle.

“In democratic systems, when you see assassinations, they’re often the result of stochastic behaviors by disgruntled or disenfranchised individuals,” Iqbal said. “By and large, democratic societies understand that assassinating an individual leader is not an efficacious mechanism for bringing about political change, because the party will just replace that individual.”

While assassinations in the U.S. have been largely similar to those elsewhere, they're often idiosyncratic, with motives that can be explicitly political, financial or personal, Zorn said.

However, "they're also often tied to political contexts in which polarization and aggressive, potentially violent rhetoric are more intense," he said.

An analysis of global assassinations published last year by economists Benjamin Jones and Benjamin Olken found that a national leader has been assassinated around the world in nearly two of every three years since 1950.

“Whether or not objectionable or illegal, assassination and assassination attempts are a persistent feature of the political landscape,” wrote Jones of Northwestern University’s Kellogg School of Management in Evanston, Illinois, and Olken, of the Massachusetts Institute of Technology in Cambridge.

On average, they wrote, successful assassinations of dictators resulted in sustained moves toward democracy.

“Small sources of randomness can have a pronounced effect on history,” they wrote.

How many attempted presidential assassinations have there been?

At least six, including two attempts on the life of President Gerald R. Ford.

∎May 10, 2005 – President George W. Bush

As Bush began to give a speech in Tbilisi, Georgia, Vladimir Arutyunian pulled the pin from a hand grenade and threw it toward the podium. It landed 65 feet away from Bush, First Lady Laura Bush and the President and First Lady of Georgia, according to the Federal Bureau of Investigation. The grenade failed to detonate thanks to a red handkerchief he had wrapped around the grenade to hide it.

∎ March 30, 1981 – President Ronald Reagan

Reagan was shot by John Hinckley Jr. after leaving a hotel in Washington, D.C., just two months after taking office.“President Reagan’s wounds were not noticed until he began to cough up blood,” states the Ronald Reagan Presidential Library & Museum. The then-70-year-old suffered a punctured lung, a broken rib and internal bleeding and underwent emergency surgery before being released after 12 days in the hospital.

∎ September 5, 1975 – President Gerald Ford

Ford was not injured when a gun in the hand of his would be assassin, Lynette "Squeaky" Fromme, did not fire during the attempt in Sacramento, California, according to the Gerald R. Ford Presidential Library and Museum. Seventeen days later, Sara Jane Moore attempted to shoot Ford, missing on the first shot, and deflected by bystander Oliver Sipple, on the second.

∎November 1, 1950 – President Harry S. Truman

Two Puerto Rican nationalists, Griselio Torresola and Oscar Collazo, opened fire at Blair House, in an attempt to assassinate the president, who was staying inside the residence during White House renovations. U.S. Army Private Leslie Coffelt of the White House Police Force was killed.

∎ January 30, 1835 – President Andrew JacksonA gunman attempted to shoot Jackson but the gun misfired, according to U.S. Supreme Court documents.

How many presidential assassinations have there been?

Four, starting with the death of President Abraham Lincoln in 1865.

∎ November 22, 1963: President John. F. Kennedy

Kennedy, 46, was riding in a motorcade with First Lady Jackie Kennedy in Dallas when he was shot and killed by Lee Harvey Oswald. Then-Texas Democratic Gov. John Connally, who was also in the car, was injured.

∎ September 6, 1901: President William McKinley

McKinley, 58, was shot at the Pan-American Exposition in Buffalo, New York during his second term when he reached out to shake the hand of Leon Czolgosz, who shot him in the stomach. McKinley died a week later at 58.

∎ July 2, 1881: President James A. Garfield

Garfield, 49, was shot in the back and shoulder by Charles Guiteau, a supporter of Vice President Chester A. Arthur while waiting for a train in Washington, D.C. He died two months after the shooting, mostly from an infection caused by doctors who didn't wash their hands when examining him. Arthur succeeded him as president.

∎ April 14, 1865: President Abraham Lincoln

Lincoln was shot from behind by actor John Wilkes Booth while watching a play at Ford's Theater in Washington D.C.

Which US presidential candidates have been assassinated or survived an assassination attempt?

Two men were assassinated, more than 100 years apart, and two other candidates survived assassination attempts.

∎ June 5, 1968: Senator Robert F. Kennedy

While campaigning for president, the younger brother of the late President John F. Kennedy, was shot twice at the Ambassador Hotel by Palestinian activist Sirhan Sirhan. Kennedy, 42, died 25 hours later.

∎ June 27, 1844: Mayor Joseph SmithFounder of The Church of Jesus Christ of Latter-Day Saints and Reform presidential candidate Joseph Smith was targeted for his Mormon beliefs. He and his brother were shot to death by a mob in a jail in Carthage, Illinois, while awaiting trial on charges Smith had incited a riot by ordering the destruction of a newspaper that had published critiques of him and his church, according to the University of Illinois, Urbana Champaign.

∎ May 15, 1972 – George WallaceWallace, governor of Alabama, was paralyzed below the waist after being shot five times by Arthur Bremer while campaigning for president in Laurel, Maryland.

∎ October 14, 1912 – Theodore RooseveltWhile running for president three years after his previous term ended, former President Theodore Roosevelt was shot in the chest at a campaign rally in Milwaukee. A speech manuscript and an eyeglasses case in his breast pocket appeared to save his life, according to the Library of Congress. Roosevelt delivered the speech he had planned for the crowd before agreeing to see medical help.

How many assassinations and assassination attempts have there been of other presidential candidates and U.S. elected officials?

Five assassinations have occurred and more than a half-dozen attempts, including the following:

∎ June 14, 2017 – Rep. Steve Scalise

Scalise, R-La., then House Majority Whip, was shot and 4 others were injured at a practice for the Republican congressional baseball team. The alleged shooter, James T. Hodgkinson, 66, a Belleville, Illinois, home inspector, was killed at the scene.

∎ Jan. 8, 2011 – Sen. Gabrielle Giffords

Giffords, D-Ariz., survived an assassination attempt when she was shot in the head during a public event in Tucson. Jared Loughner, armed with a semi-automatic pistol and 60 rounds of ammunition, pled guilty to charges related to killing six and injuring 13, including Giffords, who was left with permanent injuries.

∎ April 1993 – Former President George H. W. Bush

Kuwaiti authorities arrested a team of terrorists for plotting to assassinate the former president during an official visit to Kuwait City. The team confessed they had been recruited, trained and equipped by Iraqi intelligence agents but their plan failed.

∎ Nov. 18, 1978 – Rep. Leo Ryan

Ryan, D-Calif., was killed while visiting Guyana to investigate the activities of the People’s Temple cult led by Jim Jones. Ryan, three journalists and a cult defector died after being shot multiple times while boarding an airplane to leave Jonestown. More than 900 others died that day during a massacre and murder suicides.

∎ February 15, 1933 – President-elect Franklin D. Roosevelt

Roosevelt stood on the backseat of an open car to deliver a speech in Miami. Afterward, Guiseppe Zangara fired five shots at Roosevelt from close range, according to the Franklin D. Roosevelt Presidential Library and Museum. Roosevelt was not injured but Chicago Mayor Anton Cermak died as a result of his injuries. Three others also were injured.

∎ Jan. 29, 1973 – Sen. John Stennis Stennis, D-Miss., was mugged and shot outside his Washington D.C. home.

∎ March 1, 1954 – United States Capitol Shooting IncidentRepresentatives Kenneth Roberts, D-Ala., Ben Jensen, R-Iowa, George Fallon, D-Md., Clifford Davis, D-Tenn., and Alvin Bentley, R-Mich., were shot by a group of Puerto Rican nationalists outside the Capitol Building.

∎ September 8, 1935 – Sen. Huey Long Long, D-La., was killed in the Louisiana State Capitol building during an exchange of gunfire between his bodyguards and Carl Weiss, shortly after the state legislature passed a bill reconfiguring the district of Weiss's father-in-law, Judge Benjamin Henry Pavy, to deny him reelection.

∎ April 24, 1905 – Rep. John McPherson Pinckney Rep. Pinckney, D-Texas, his brother and two others were shot and killed when a meeting about prohibition issues in his home state turned violent. One other person was wounded.

∎ July 31, 1869 – Rep. Thomas Haughey Haughey, R-Ala., was shot in the stomach during a physical altercation after giving a speech in Courtland, Alabama. He died five days later.

∎ October 22, 1868 – James HindsRep. Hinds, R-Ark., was shot in the back and killed by George A. Clark, a member of the Ku Klux Klan and secretary of the local Democratic committee.

Other attacks against federal elected officials

• October 2001 – Letters containing anthrax spores were delivered to the offices of Senators Patrick Leahy and Tom Daschle, but no one was injured.
• July 24, 1998 – A gunman carrying a pistol opened fire inside the U.S. Capitol, killing two Capitol Police officers, Jacob Chestnut and John Gibson . A tourist was injured.
• November 1979 – Suzanne Osgood was arrested with a hunting knife in the reception area of the office of Sen. Edward Kennedy.
• Three attempted bombings were reported in the early 1900s, including one bomb sent to Sen. Huey Long's office, another in the vehicle of Rep. Charles A. Eaton, R-N.J and another bound for Rep. John L. Burnett, D-Ala., according to the Congressional Research Service.
• Three officials died as a result of dueling over a period of 30 years between 1831 and 1859, including Sen. David Broderick of California in 1869; Maine Rep. Jonathan Ciller in 1838 and Spencer Pettis in 1831.

Contributing: N'dea Yancey-Bragg, Sam Woodward and Kim Luciani