The two most notable U.S. school shootings in the early 1970s were the Jackson State killings in May 1970, where police opened fire on the campus of Jackson State University and the Kent State shootings also in May 1970 where the National Guard opened fire on the campus of Kent State University.
The mid to late 1970s is considered the second most violent period in U.S. school history with a series of school shootings, most notably were;
February 2, 1971: Philadelphia, Pennsylvania Teacher Samson L. Freedman, 56, was shot to death as he left Morris E. Leeds School, by Kevin Simmons, 14. Freedman had suspended Simmons earlier in the day for cursing in the hallway.
November 8, 1971: Grove, Oklahoma, School custodian, Jim "James" Underwood brought a .22-caliber revolver to school hidden in a brown paper bag. School principal, T.J. Melton, 49, was shot in the left shoulder, left ear and in the top of his head, according to published reports. He died around 9 a.m. and Underwood was charged the next day with first-degree murder. 
January 5, 1972: Washington, DC Fifth-grade teacher Margaret Brooks, 57, was shot to death in front of her students by her estranged husband James A. Brooks.
January 17, 1974: Chicago, Illinois Elementary school principal Rudolph Jezek, Jr., 52, was shot to death in his office by Steven Guy, 14, a former student said to be angry at being transferred from the school to a social adjustment center.
December 30, 1974: Olean, New York, Anthony Barbaro, a 17-year-old Regents scholar armed with a rifle and shotgun, kills three adults and wounds 11 others at his high school, which was closed for the Christmas holiday. Barbaro was reportedly a loner who kept a diary describing several "battle plans" for his attack on the school.
February 12, 1976: At Detroit, Michigan's Murray-Wright High School, about six intruders, who according to police looked like junior high students or younger, entered Murray Wright. According to the police they were searching for a student who had "stolen one of their girlfriends." Two teachers discovered the intruders and asked them to leave. A security guard escorted the intruders down a hallway as about six Murray-Wright students followed the intruders as they were leaving. Outside of the door to the school, two of the intruders brandished guns and fired into the group., shooting and injuring five students. One of the injured was treated and released and the others were treated at Henry Ford Hospital.
May 1976: Randy Truitt a high school student at US Grant High School in Oklahoma City, Oklahoma was shot and killed by James Briggs at the school, leaving several injured.
June 12, 1976: California State University, Fullerton massacre, where the school's custodian opened fire with a semi-automatic rifle in the library on the California State University, Fullerton campus killing 7, and wounding 2.
November 10, 1976: Detroit, Michigan Second grade teacher Bettye McCaster, 45, was shot to death in front of her 29 students at Burt Elementary School, by her estranged husband, Al Lewis.
February 9, 1978: A 15-year-old student was shot and killed by another student at Hayes Junior High School in St. Albans, WV.
February 22, 1978: Lansing, Michigan After being taunted for his beliefs, a 15-year-old self-proclaimed Nazi, kills one student and wounds a second with a Luger pistol.
May 18, 1978: Austin, Texas John Daniel Christian, a 13-year-old and son of LBJ's former Press Secretary and prominent Texas political figure (George Christian), walked into his 8th grade English class at Murchison Junior High School (now Murchison Middle School) and shot to death his English teacher, Wilbur "Rod" Grayson, with George Christian's .22 gun, in front of approximately 30 classmates. John Christian was never prosecuted, allegedly, because he was a minor at the time but, most likely, because his father pulled strings to avoid prosecution. John Christian is now a practicing attorney in Austin, Texas, licensed by the Texas State Bar Association. 
January 29, 1979: Grover Cleveland Elementary School Shootings, California, where 16-year-old Brenda Ann Spencer opened fire with a rifle, a gift from her father, killing 2 and wounding 9.
The early 1980s saw many single shootings, similar to the 1970s:
March 26, 1980: Big Rapids, Michigan, Robert Brauer, Business Professor, was shot by a student Thomas Kakonis at Ferris State College. Robert Brauer had failed the student on an examination. At 20 years old, Thomas Kakonis was the son of an associate dean at the college. 
April 7, 1982: Littleton, Colorado, Deer Creek Jr. High School The gunman, 14-year-old Jason Rocha, was a student at Deer Creek. Rocha shot and killed 13 year-old Scott Darwin Michael.
The early 1980s saw only a few multi-victim school shootings, including:
January 20, 1983: St. Louis County, Missouri Parkway South Middle School The eighth grade shooter brought a blue duffel bag containing two pistols and a murder/suicide note that outlined his intention to kill the next person heard speaking ill of his older brother, Ken, to school. He entered a study hall classroom and opened fire, hitting two fellow students. The first victim was fatally shot in the stomach, and the second victim received a non-fatal gunshot wound to the abdomen. He said, "no one will ever call my brother a pussy again," then committed suicide.
According to the Center to Prevent Handgun Violence, in the United States, from September 1986 to September 1990:
At least 71 people (65 students and 6 school employees) had been killed with guns at school.
201 were severely wounded by gun fire.
242 individuals were held hostage at gunpoint.
According to a 1987 survey conducted by the American School Health Association, " 3% of the boys reported having carried a handgun to school at least once during the school year; 1% reported carrying a handgun on a daily basis."
The late 1980s began to see a major increase in school shootings, including:
May 17, 1984: Des Moines, Iowa While students in a French class at Southeast Polk High School were taking a test in the hallway, a 17 year old boy shot and killed a 16 year old female student before firing a single shot into his own head, killing himself.
January 22, 1985: Goddard, Kansas James Alan Kearbey, 14, armed with a M1-A semiautomatic rifle and a .357-caliber handgun, killed principal Joseph McGee and wounded two teachers and a student at his Junior high school. He pleaded no contest and served seven years in a state youth facility.
September 4, 1985: Richmond, Virginia At the end of the second day of school at East End Middle School, a 12 year old boy shot a girl with his mother's gun.
October 18, 1985: Detroit, Michigan During halftime of the homecoming football game between Northwestern High School and Murray-Wright High School, a boy who was in a fight earlier that day pulled out a shotgun and opened fire, injuring six students.
November 26, 1985: Spanaway, Washington A 14 year old girl shot two boys fatally, then killed herself with a .22-caliber rifle at Spanaway Junior High School.
December 9, 1985: Philadelphia, Pennsylvania At Archbishop Ryan High School for Boys, a 22 year old Mental health patient took 6 students hostage with what ended up being a starter pistol. No one was hurt in the ordeal.
December 10, 1985: Portland, Connecticut At Portland Junior High School, the Principal was having a heated discussion with a 13 year old male eighth grader when he locked the boy inside an office. The student then pulled out a 9mm firearm and opened fire. The bullet shattered the glass door and struck the left forearm of the secretary, and the glass injured the Principal. The boy fled for the 2nd floor, where he shot a janitor in the head. The boy then took a seventh grader hostage. The boy's father and another family member came to the school and talked to him over the intercom system. After 45 minutes, he tossed the gun out a school window and was taken into custody.
April 1986:Slidell, Louisiana 13 year old gifted Boyet Junior High School Student Matt Cooper put a .45 caliber pistol to his head and shot himself in class.
May 16, 1986: The Cokeville Elementary School hostage crisis In a ransom scheme, David and Doris Young, both in their forties, took 150 students and teachers hostage. Their demand for $300 million dollars came to an abrupt end when Doris accidentally set off a bomb, killing herself and injuring 78 students and teachers. David wounded John Miller, a teacher who was trying to flee, then killed himself.
December 5, 1986: Fergus High School Lewistown, Montana A student shot and killed a substitute teacher in a classroom at his high school, then wounded a vice principal and two classmates. The 14-year-old student, who was armed with a large-caliber revolver, was arrested at his home after his parents turned him over to police following the 1:22 p.m. shootings at Fergus High School
March 2, 1987: De Kalb, Missouri Honours student Nathan Ferris, 12, killed a classmate and then himself.
April 16, 1987: a student at Detroit, Michigan's Murray-Wright High School entered the school parking lot and shot 17-year old Chester Jackson, a junior running back, in the head, killing him. He attacker went into the gymnasium and shot 18-year old Damon Matthews, a basketball player, in the face. Tomeka Turner, an 18-year old, was wounded. Risen said that Turner's injuries occurred "apparently in the school's corridors as the attacker fled the building."
December 16, 1987: Mayde Creek High School near Katy, Texas A 15-year-old boy, Ramesh D. Tumalad, apparently despondent over love, shot himself to death in his Algebra class as his classmates looked on. The girl with whom he was having romantic problems was among those in the class. The shooting occurred about 10 a.m.; the teacher was standing near the door taking attendance when Ramesh, seated in the rear of room, shot himself. There were about 25 pupils in the class. 
May 20, 1988: Winnetka, Illinois 30 year old Laurie Dann shot and killed one elementary school student and wounded five others, then took a family hostage and shot a man before killing herself.
September 26, 1988: Greenwood, South Carolina In the cafeteria of the Oakland Elementary School 19 year-old James William Wilson Jr., shot and killed Shequilla Bradley, 8 and wounded eight other children with a 9-round .22 caliber pistol. He went into the girls restroom to reload where he was attacked by Kat Finkbeiner, a Physical Education teacher. James shot her in the hand and mouth. He then entered 3rd grade classroom and wounded six more students.
December 16, 1988: Virginia Beach, Virginia Nicholas Elliott, 15, opened fire with a SWD Cobray M-11 semiautomatic pistol on his teachers at the Atlantic Shores Christian School. His first shots struck teacher Karen Farley in the arm; when she went down he killed her at point blank range. Nicholas then injured Sam Marino. He turned the Cobray toward his classmates, but the gun jammed and he was quickly subdued by M. Hutchinson Matteson, a teacher, before he could fire another round.
January 17, 1989: Cleveland School massacre of Stockton, California where 5 school children were killed and 30 wounded by a single gunman firing over 100 rounds into a schoolyard from an AK-47, in which the perpetrator later took his life.
Main articles: Columbine High School massacre, Westside Middle School massacre, and Lindhurst High School shooting
From the late 1980s to the early 1990s, the United States saw a sharp increase in guns and gun violence in the schools. According to a survey conducted by The Harvard School of Public Health, "15% [of students surveyed] said that they had carried a handgun on their person in the past 30 days, and 4% said that they had taken a handgun to school in the past year," a sharp increase from just five years earlier. By 1993, the United States saw one of the most violent periods in school shooting incidences.
January 8, 1991, Jeremy Delle, a 15-year-old sophomore who had recently transferred to the school, killed himself with a .357 Magnum in front of his second-period English class. He was described by schoolmates as "acting sad". After coming into class late that morning, he was told to get an attendance slip from the school office. He left and returned with a .357 revolver. He walked to the front of the class and announced, "Miss, I got what I really went for." Delle then put the gun into his mouth and pulled the trigger. The incident inspired the Pearl Jam song "Jeremy". The band's lead singer, Eddie Vedder, read a newspaper account of the incident and was moved to write the song almost immediately
May 1, 1992: Olivehurst, California Eric Houston, 20, killed four people and wounded 10 in an armed siege at his former high school. Prosecutors said the attack was in retribution for a failing grade.
According to the National School Safety Center, since the 1992-1993 U.S. school year there has been a significant decline in school-associated violent deaths (deaths on private or public school property for kindergarten through grade 12 and resulting from schools functions or activities):
1992–1993 (44 Homicides and 55 Deaths resulting from school shootings in the U.S.)
1993–1994 (42 Homicides and 51 Deaths resulting from school shootings in the U.S.)
1994–1995 (17 Homicides and 20 Deaths resulting from school shootings in the U.S.)
1995–1996 (29 Homicides and 35 Deaths resulting from school shootings in the U.S.)
1996–1997 (23 Homicides and 25 Deaths resulting from school shootings in the U.S.)
1997–1998 (35 Homicides and 40 Deaths resulting from school shootings in the U.S.)
1998–1999 (25 Homicides from school shootings in the U.S.)
1999–2000 (25 Homicides from school shootings in the U.S.)
According to the U.S. Department of Education, in the 1998-1999 School Year, 3,523 students (57% High School, 33% Junior High, 10% Elementary) were expelled for bringing a firearm to school.
The late 1990s started to see a major reduction in gun related school violence, but was still plagued with multiple victim shootings including;
January 12, 1995: Seattle Washington A student left school during the day and returned with his grandfather's 9mm. He wounded two students. The incident is portrayed in the documentary Cease Fire.
October 12, 1995: Blackville, South Carolina A suspended student shot two math teachers with a .32 caliber revolver.
November 15, 1995: Lynnville, Tennessee A 17-year-old boy shot and killed a student and teacher with a .22 rifle.
February 2, 1996: Moses Lake, Washington Two students and one teacher killed, one other wounded when 14-year-old Barry Loukaitis opened fire on his algebra class.
February 19, 1997: Bethel, Alaska Principal and one student killed, two others wounded by Evan Ramsey, 16.
October 1, 1997: Pearl, Mississippi Two students killed and seven wounded by Luke Woodham, 16, who was also accused of killing his mother. He and his friends were said to be outcasts who worshiped Satan.
November 27, 1997: West Palm Beach, Florida Conniston Middle School 14-year-old John Kamel was fatally shot in the chest at 8:40 a.m. outside school on a sidewalk by 14-year-old Tronneal Mangum after an argument over an Adidas watch that Mangum had taken from Kamel.
December 1, 1997: West Paducah, Kentucky Three students killed, five wounded by Michael Carneal, 14, as they participated in a prayer circle at Heath High School.
December 15, 1997: Stamps, Arkansas Two students wounded. Colt Todd, 14, was hiding in the woods when he shot the students as they stood in the parking lot
March 24, 1998: Jonesboro, Arkansas Four students and one teacher killed, ten others wounded outside as Westside Middle School emptied during a false fire alarm. Mitchell Johnson, 13, and Andrew Golden, 11, shot at their classmates and teachers from the woods
April 24, 1998: Edinboro, Pennsylvania One teacher, John Gillette, was killed and two students wounded at a dance at James W. Parker Middle School. Andrew Wurst, 14, was charged.
May 21, 1998: Springfield, Oregon Two students killed, 22 others wounded in the cafeteria at Thurston High School by 15-year-old Kip Kinkel. Kinkel had been arrested and released a day earlier for bringing a gun to school. His parents were later found dead at home, shot to death by their son
June 15, 1998: Richmond, Virginia One teacher and one guidance counselor wounded by a 14-year-old boy in the school hallway
May 19, 1998: Fayetteville, Tennessee High School Senior Jacob Davis shot and killed eighteen year-old Robert "Nick" Creson in a dispute over a girl. He then lay down his rifle and waited with his head in his hands for the police to come. He was convicted of First Degree Murder and is serving life in prison.
December 10, 1998: Detroit, Michigan One professor killed by a graduate student. 
April 20, 1999: Columbine, Colorado 14 students (including 2 shooters) and one teacher killed, 27 others wounded at Columbine High School. Eric Harris, 18, and Dylan Klebold, 17, had plotted for a year to kill at least 500 and blow up their school. At the end of their hour-long rampage, they turned their guns on themselves.
May 20, 1999: Conyers, Georgia Six students injured at Heritage High School by Thomas Solomon, 15, who was reportedly depressed after breaking up with his girlfriend
November 19, 1999: Deming, New Mexico One student killed at Deming Middle School by Victor Cordova Jr., 13.
Main articles: Virginia Tech massacre, Red Lake massacre, Amish school shooting, and Northern Illinois University Shooting
February 29, 2000: Buell Elementary School, Flint, Michigan; 6-year-old Dedrick Owens, youngest-ever school shooter. Kayla Rolland was the single fatality.
May 26, 2000: Lake Worth, Florida Lake Worth Middle School Florida teacher Barry Grunow was fatally shot by his student, 13-year-old Nathaniel Brazill, who had returned to school after being sent home at 1 p.m. by the assistant principal for throwing water balloons. Brazill returned to school on his bike with a 5 inch Raven and four bullets stolen from his grandfather the week before. Brazill was an honor student. Grunow was a popular teacher and Brazill's favorite.
August 28, 2000: University of Arkansas shooting at Fayetteville, Arkansas At approximately 12:14 pm, Dr. John R. Locke, 67, Director of the Comparative Literature Program was shot and killed in his office by James E. Kelly, 36, a Comparative Literature PhD candidate who had recently been dismissed from the program for lack of progress towards his degree. Kelly shot Dr. Locke three times before taking his own life in Dr. Locke's office after it was cordoned off by campus police.
September 26, 2000: Darrel Johnson, 13, offender in Louisiana school shooting with 1 student fatality.
March 5, 2001: Charles Andrew William, age 15, offender in California school shooting, 15 wounded 2 of which died.
March 30, 2001: Donald R. Burt Jr., age 18, offender in Indiana school shooting with 1 student fatality.
September 24, 2003: John Jason McLaughlin, age 15, offender in Minnesota school shooting with 2 student fatalities.
February 2, 2004: Unidentified offender in Washington, DC school shooting with 1 student fatality.
May 7, 2004: Unidentified 17 year old offender in Maryland school shooting with 1 student fatality.
March 21, 2005: Jeff Weise, 16 year old offender in Minnesota school shooting. Fatalities include 1 teacher, 5 students, 1 security guard, 2 relatives.
November 8, 2005: Kenny Bartley, age 15, offender in Tennessee school shooting with 1 principal fatality.
August 24, 2006: Christopher Williams walked into Essex Elementary School and opened fire, killing teacher Alicia Shanks after killing his ex-girlfriend's mother, Linda Lambessis, at home. Essex, VT
September 29, 2006: Eric Hainstock, 15 year old offender in Weston High School shooting, walked in the school building and shot the high school principal with a handgun after a custodian disarmed him of a shotgun in Cazenovia, Wisconsin.
October 2, 2006: Charles Carl Roberts IV, a 32 year old a milk truck driver, murdered five Amish girls and injured five others before killing himself in an Amish school in the hamlet of Nickel Mines, in Bart Township, Lancaster County, Pennsylvania.
April 16, 2007: Seung-Hui Cho, age 23, offender in Virginia Tech University shooting. 32 students and faculty were killed, along with another 17 students and faculty injured in two separate attacks on the same day.
February 14, 2008: The Northern Illinois University shooting was a school shooting that took place on February 14, 2008, during which Steven Kazmierczak shot multiple people on the campus of Northern Illinois University in DeKalb, Illinois, United States, killing five and injuring 21, before committing suicide.
October 26, 2009: A graduate student fatally shot himself in the presence of a professor, in the professor's office, on the Tempe campus of Arizona State University. http://blogs.phoenixnewtimes.com/valleyfever/2009/10/asu_grad_student_shoots_himsel.php