(CNN)Here is some background information about the Secret Service, a federal agency tasked with protecting the president of the United States, among many other responsibilities.
The Secret Service is one of the country's oldest federal investigative agencies, founded in 1865 to stop counterfeiters.
There are approximately 3,200 special agents and an additional 1,300 uniformed officers who guard the White House, the Treasury building and foreign diplomatic missions in Washington.
In addition to protecting the First Family, the Secret Service also provides security for the vice president, the president-elect, the vice president-elect, former presidents and their families, presidential candidates, visiting heads of state and representatives of the United States performing special missions overseas.
After September 11, 2001, the Secret Service took on new responsibilities, overseeing security at non-political events that could be targets for terrorists, like the Super Bowl. Even as the scope of its mission broadened, the agency did not receive adequate funding, according to a House Oversight Committee report. Budget cuts, poor management and low morale led to an exodus of employees. Between 2011 and 2015, the number of full-time workers at the agency fell from 7,024 to 6,315, according to the House Oversight Committee.
July 5, 1865 - The Secret Service is established as an investigative unit within the Department of Treasury. At the time, the country was awash with forged currency. Between one-third and half of the money in circulation was counterfeit, according to some estimates.
1867 - The role of the agency expands to include investigations of mail theft, bootlegging, smuggling and fraud.
1894 - The Secret Service provides part-time protection for President Grover Cleveland after the agency discovers an assassination plot while probing a group of gamblers.
1898 - A White House detail is established to protect President William McKinley during the Spanish-American War. After the end of the war, Secret Service operatives continue to watch over the White House part time.
September 6, 1901 - McKinley is shot and critically wounded during a reception in Buffalo, New York. McKinley dies eight days later and Vice President Theodore Roosevelt is sworn into office. The assassination prompts Congress to request full-time Secret Service protection for presidents.
1902 - The Secret Service establishes an around-the-clock White House detail to protect President Roosevelt.
1908 - The FBI is established, with a group of Secret Service and Department of Justice investigators.
1917 - Congress passes a law making it a federal crime to threaten the president.
November 1, 1950 - Secret Service officer Leslie Coffelt is gunned down while protecting President Harry S. Truman at the Blair House in Washington. He is the first and only Secret Service member to be killed in the line of duty guarding the president.
November 22, 1963 - President John F. Kennedy is assassinated. According to the Warren Commission, a number of agents protecting Kennedy had been out late the night before the tragedy and some violated protocol by drinking alcohol. Ultimately, the agents were not disciplined and the Warren Commission concluded that there was no misconduct.
1968 - After the assassination of Sen. Robert F. Kennedy, the Secret Service offers protection to major presidential and vice presidential candidates.
March 30, 1981 - President Ronald Reagan is shot and injured by John Hinckley Jr. Secret Service Agent Timothy McCarthy is also hit, trying to block Hinckley as he fires at Reagan. Press Secretary James Brady and a Washington police officer are also wounded.
1994 - Congress authorizes the Secret Service to help the National Center for Missing and Exploited Children. The agency provides forensic and technical assistance.
April 19, 1995 - Domestic terrorists bomb the Alfred P. Murrah Federal Building in Oklahoma City, which housed a regional Secret Service office. Six agency employees are among the 168 people killed in the attack.
September 11, 2001 - The Secret Service's New York field office in 7 World Trade Center is destroyed during the terror attacks, and Special Officer Craig Miller is killed.
March 2003 - The Secret Service moves from the Treasury Department to the Department of Homeland Security. Despite its transfer to DHS, the agency continues to investigate financial crimes.
November 11, 2011 - A gunman fires an assault rifle at the White House, hitting the residential wing of the building at least seven times. Secret Service supervisors fail to recognize the danger, dismissing the gunfire as a gang-related shootout rather than an attack on the White House, according to the Washington Post. Four days later, a housekeeper and a White House usher spot bullet holes in the residence. Five days after the shooting, the gunman, Oscar Ramiro Ortega-Hernandez is arrested at a Pennsylvania hotel. In 2014, Ortega-Hernandez is sentenced to 25 years in federal prison.
April 2012 - After allegations of misconduct involving heavy drinking and prostitutes, 11 Secret Service members are recalled to the United States from Colombia, where they had been working on security ahead of a visit by President Barack Obama.
February-March 2013 - Mark Sullivan retires as director of the Secret Service. Julia Pierson takes his place. She is the agency's first female director.
May 2013 - A senior agent from the presidential detail creates a fuss at a Washington hotel, trying to get back into a woman's room, fearing he left behind a bullet from his gun, according to the Washington Post. An internal review reveals the agent and another member of Obama's detail had sent inappropriate emails to a female coworker. One of the agents is later fired, and the other is reassigned.
December 10, 2013 - During a memorial service for Nelson Mandela in South Africa, a man with forged security credentials stands feet away from President Obama. The man pretends to be a sign language interpreter, taking the stage with Obama and other world leaders. He later tells reporters he is mentally ill. The Secret Service faults South African event organizers for failing to vet the imposter.
March 23, 2014 - A member of the Secret Service's elite counter assault team is found passed out in an Amsterdam hotel lobby after a night of alleged partying, according to the Washington Post. He and two other members of the presidential detail are recalled home and placed on administrative leave.
September 16, 2014 - Agents violate protocol by allowing an armed security guard to ride in an elevator with the president during a visit to the Centers for Disease Control and Prevention in Atlanta. The guard uses his cellphone to take pictures of Obama in his limousine. He is detained by Secret Service agents, who learn he is carrying a gun. Although the agency initially claimed the CDC did not tell them the guards were armed, the 2015 House Oversight Committee report concludes the CDC had notified the Secret Service that its security personnel carry weapons. The report also states the Secret Service failed to conduct a background check on the guard, and waited two weeks to tell the president about the breach. The guard loses his job after the incident.
October 1, 2014 - In the wake of several security breaches, Pierson resigns as director of the Secret Service. Joseph Clancy, a former special agent from the president's security detail, steps in as interim director.
October 28, 2014 - The New York Times reports that the DHS investigator overseeing a government probe into the Cartagena prostitute scandal quit his job after authorities in Florida caught him entering the suspected brothel.
December 2014 - A government panel established after a White House intruder incident in September releases a report recommending more effective fencing around the executive mansion. The review also describes a leadership vacuum within the agency, along with a lack of focus and a need for more training. The panel recommends hiring 85 new agents and 200 uniformed officers to prevent future breaches.
January 14, 2015 - The Washington Post reports that four high-ranking Secret Service executives are losing their jobs as the agency undergoes a change in leadership prompted by the breaches and scandals.
February 18, 2015 - President Obama chooses Clancy to be the director of the agency, going against recommendations to bring in an outsider to help the Secret Service implement reforms.
March 4, 2015 - Two Secret Service supervisors returning to the White House from a party unwittingly drive into a barricade and interfere with an investigation of a suspicious package. The supervisors were drinking at the party, according to a congressional review of the incident.
April 8, 2015 - A senior supervisor is placed on administrative leave amid allegations he sexually assaulted a female colleague at the office after hours, the Washington Post reports.
June 9, 2015 - The Washington Post reports that dozens of new Secret Service hires have been posted in sensitive locations without proper national security clearances. An agency spokesman tells the Post the vetting process is being expedited so all the new staffers will be cleared within three days.
September 25, 2015 - The DHS's Office of the Inspector General releases a memorandum revealing that Secret Service employees improperly accessed the personnel file for Congressman Jason Chaffetz, who had once applied for a job with the agency. Chaffetz chairs the committee investigating the Secret Service. According to the memo, agency employees accessed Chaffetz's personal information approximately 60 times.
September 30, 2015 - The DHS reports a senior manager at the Secret Service encouraged employees to leak Chaffetz's job application to retaliate against the congressman. "Some information that he might find embarrassing needs to get out. Just to be fair," the manager wrote in an email.
October 21, 2015 - The DHS issues an alert, warning Secret Service management that agents are overworked and fatigued. According to the alert, two officers were discovered sleeping at their posts during an audit of security at protected buildings.
December 2015 - The House Oversight Committee issues a 438-page report, "United States Secret Service: An Agency in Crisis." The report examines the 2011 White House shooting episode, the misconduct in Colombia, the breach at the CDC and the incident involving the supervisors driving into a crime scene. The review lists six additional breaches that took place over the course of a single month, including a security lapse that enabled an uninvited guest to go backstage at a function and speak to the president. The committee proclaims that the agency has failed to implement many of the reforms recommended by the government panel in 2014. In conclusion, the committee declares that "the agency's recent public failures are not a series of isolated events, but the product of an insular culture that has historically been resistant to change."
May 26, 2016 - After reviewing the conduct of 57 Secret Service personnel, "41 are receiving some level of discipline" regarding the leak of Chaffetz's job application, Secretary of Homeland Security Jeh Johnson says in a statement.
November 2015-November 2016 - The Secret Service secures 3,220 campaign stops and screens over three million people during the busy election cycle.
November 15, 2016 - The Secret Service conducts the largest seizure of counterfeit currency in the agency's history. Thirty million counterfeit US dollars and 50,000 euros are discovered in Lima, Peru.
February 14, 2017 - Secret Service Director Clancy announces his retirement to the staff. His retirement is effective March 4.
March 16, 2017 - A laptop with highly sensitive information, including floor plans and the evacuation protocol for Trump Tower, is stolen from a Secret Service agent's car in Brooklyn.