U.S. Rep. John Lewis, no stranger to protest from his days of civil-rights activism, joined other Democrats in staging a sit-in <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2F2016%2F06%2F23%2Fpolitics%2Fgallery%2Fhouse-democrats-sit-in%2Findex.html" target="_blank">at the House of Representatives</a> on Wednesday, June 22. They were trying to force votes on gun control after the <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2F2016%2F06%2F12%2Fus%2Fgallery%2Forlando-shooting%2Findex.html" target="_blank">largest mass shooting in U.S. history.</a>
U.S. Rep. John Lewis, no stranger to protest from his days of civil-rights activism, joined other Democrats in staging a sit-in at the House of Representatives on Wednesday, June 22. They were trying to force votes on gun control after the largest mass shooting in U.S. history.
From Facebook
Many of the earliest sit-ins were labor strikes. In December 1936, workers at a General Motors plant in Flint, Michigan, staged a "sit-down" strike seeking union representation.
Many of the earliest sit-ins were labor strikes. In December 1936, workers at a General Motors plant in Flint, Michigan, staged a "sit-down" strike seeking union representation.
Sheldon Dick/Hulton Archive/Getty Images
The method saw renewed use in the civil-rights movement. A pivotal moment came in 1960, when African-American college students staged a sit-in at the <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2F2010%2FUS%2F02%2F01%2Fgreensboro.four.sitins%2F">Woolworth's lunch counter</a> in Greensboro, North Carolina.
The method saw renewed use in the civil-rights movement. A pivotal moment came in 1960, when African-American college students staged a sit-in at the Woolworth's lunch counter in Greensboro, North Carolina.
Bettmann Archive/Getty Images
Sit-ins like the one in Greensboro spread across the South. Here, women protest segregation in Nashville, Tennessee, in 1960.
Sit-ins like the one in Greensboro spread across the South. Here, women protest segregation in Nashville, Tennessee, in 1960.
Bettmann Archive/Getty Images
In 1965, University of Michigan professors such as Eric Wolf, pictured, staged a "teach-in" to protest the Vietnam War.
In 1965, University of Michigan professors such as Eric Wolf, pictured, staged a "teach-in" to protest the Vietnam War.
Bettmann Archive/Getty Images
In 1969, John Lennon and Yoko Ono took the concept of a sit-in a step further, staging a "bed-in" in Amsterdam, Netherlands,<a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2F2012%2F03%2F02%2Ftravel%2Fhistoric-hotel-rooms-cnngo%2F"> and another in Montreal</a> to protest the Vietnam War.
In 1969, John Lennon and Yoko Ono took the concept of a sit-in a step further, staging a "bed-in" in Amsterdam, Netherlands, and another in Montreal to protest the Vietnam War.
Keystone/Hulton Archive/Getty Images
In 1969, students took over University Hall at Harvard, demanding the school <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2F2011%2FUS%2F03%2F03%2Fmassachusetts.harvard.rotc%2F">end its Reserve Officer Training Corps program.</a> The violent removal of students drew nationwide criticism.
In 1969, students took over University Hall at Harvard, demanding the school end its Reserve Officer Training Corps program. The violent removal of students drew nationwide criticism.
Ted Dully/The Boston Globe/Getty Images
Feminist activists held an 11-hour <a href="index.php?page=&url=http%3A%2F%2Fcontent.time.com%2Ftime%2Fspecials%2Fpackages%2Farticle%2F0%2C28804%2C2088114_2087975_2087966%2C00.html" target="_blank" target="_blank">sit-in at Ladies' Home Journal</a> in 1970, demanding a woman replace the magazine's male editor.
Feminist activists held an 11-hour sit-in at Ladies' Home Journal in 1970, demanding a woman replace the magazine's male editor.
Jack Smith/NY Daily News/Getty Images
In 1977, disability rights protesters occupied the San Francisco offices of the Department of Health, Education and Welfare, demanding the federal government implement a law protecting the rights of the disabled.
In 1977, disability rights protesters occupied the San Francisco offices of the Department of Health, Education and Welfare, demanding the federal government implement a law protecting the rights of the disabled.
JP/AP
In 1997, environmental activist Julia Hill began a two-year sit-in, <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2FTECH%2Fscience%2F9806%2F22%2Frecord.treesitter%2F">living in a California redwood tree</a> to protest logging. Here, she is pictured in a similar 2006 effort.
In 1997, environmental activist Julia Hill began a two-year sit-in, living in a California redwood tree to protest logging. Here, she is pictured in a similar 2006 effort.
ROBYN BECK/AFP/AFP/Getty Images
In September 2011, participants in the Occupy Wall Street protest met in a park in New York. About 1,000 demonstrators gathered to protest the U.S. capitalist system.
In September 2011, participants in the Occupy Wall Street protest met in a park in New York. About 1,000 demonstrators gathered to protest the U.S. capitalist system.
DON EMMERT/AFP/Getty Images
In April of this year, hundreds of "Democracy Spring" protesters were arrested during a Capitol Hill sit-in.
In April of this year, hundreds of "Democracy Spring" protesters were arrested during a Capitol Hill sit-in.
ANDREW CABALLERO-REYNOLDS/AFP/Getty Images