September 11 memorial in Tampa, Florida (Photo Credit: Walter from Tampa/St Petersburg, Florida CC BY 2.0 via Wikimedia Commons0

Those of you born post-2001 are accustomed to the strict air travel rules that forbid taking even water past security gates. However, airports were not always like that. Seventeen years ago, passengers were not only allowed to carry on board all liquids, but also “dangerous” items such as baseball bats, box cutters, darts, knitting needles, scissors, and even four-inch blades. That changed on September 11, 2001, when members of the Islamic extremist organization Al Qaeda used airplanes as weapons to carry out the deadliest terrorist attacks on American soil in U.S. history.

The fateful Tuesday appeared to be like any other day. East Coast residents were at, or on their way to, work or school, while those on the West Coast were still snoozing. However, things were not as tranquil for the passengers aboard United Airlines Flights 93 and 175 and American Airlines Flights 77 and 11. That’s because among the passengers were 19 terrorists, split into four teams, each with an experienced pilot. The cross country flights, heading from the East Coast to either Los Angeles or San Francisco, were selected to ensure the airplanes had ample fuel to enable the hijackers to inflict maximum damage.

Aircraft crashes into World Trade Center (Photo Credit: APHOrisma via Flckr Public Domain)

To those on the ground, the first indication that something was terribly wrong came at 8:46 a.m. (EST) when American Flight 11 crashed into One World Trade Center, or North Twin Tower. The impact, witnessed by thousands of onlookers, created a gaping hole all the way from the 93rd to 99th floor. While horrifying, everyone, including experts, assumed the crash was an accident caused by pilot error. However, that changed at 9:03 a.m. EST when United Flight 175 hurtled into Two World Trade Center, or South Twin Tower. Before anyone had time to process the tragic events, American Flight 77 struck the Pentagon building in Washington DC. Shortly after, United Flight 93 crash-landed in an empty field on the outskirts of Shanksville, Pennsylvania. By then, it was evident that America had suffered a series of orchestrated terrorist attacks.

Meanwhile in New York, firefighters, paramedics, and police officers rushed to assist and evacuate the thousands of survivors inside the damaged Twin Towers. While their quick action helped save 18,000 lives, many of the brave first responders did not make it out alive. That’s because the fires, sparked by the well-fueled airplanes, melted the steel support trusses that framed the 110 floors of each building. This, combined with the damage caused by the initial impact of the aircraft, resulted in both towers collapsing into a massive heap of cement and steel less than two hours after the airplanes hit the respective buildings. As the structures collapsed, they ignited fires in the surrounding buildings, leading to the collapse of World Trade Center Seven as well. Fortunately, everyone in the area had been safely evacuated. Though the Pentagon building did not collapse, the airplane attack did result in the deaths of 184 people. All in all, 2,977 innocent people from 93 nations lost their lives on 9/11/2001.

A clock, frozen at the time of impact on the Pentagon (Photo Credit: Airforce Staff Sgt. Larry A. Simmons)

The death toll would have been even higher had United Flight 93 succeeded in reaching the terrorist’s intended target — the US Capitol building in Washington. However, when New Jersey resident Jeremy Glick called his wife to tell her his flight had been hijacked, he heard about the attacks on the Twin Towers. Determined not to allow the terrorists to use the flight as a weapon, the brave 31-year-old called again a few minutes later to inform her that all the passengers and crew were uniting to try to overpower the hijackers. Shortly after, the plane was seen meandering across the skies before nose-diving into an abandoned coalfield in Shanksville, Pennsylvania. Though all 33 passengers and seven crew members perished, their heroic act saved the country from an even bigger catastrophe.

New York National Guard soldiers and New York firefighters attempt to clean-up the rubble (Photo Credit: New York National Guard)

Following the terrorist attacks, there was much debate about what to do with the land where the World Trade Center complex once stood. Some advocated erecting an even bigger structure to show the terrorists that Americans were not intimidated by their cowardly act, while others wanted the site to become a memorial to ensure that the innocent lives lost would not be forgotten. After much deliberation, it was decided that both were essential.

Today, the site, once dubbed “Ground Zero,” is home to four new towers, including the 1,776-feet-tall One World Trade Center, or "Freedom Tower.” Two more skyscrapers are in various stages of planning and construction. Adjacent to the Freedom Tower lies an elegant memorial featuring twin reflecting pools with the names of all the victims etched into the bronze-paneled edges, and a National September 11 museum. In Shanksville, a separate monument honors the 33 passengers and seven crew members of United Flight 93. Visitors to both can view exhibits and artifacts commemorating the 9/11 tragedy and listen to playbacks of messages left by the passengers to their loved ones before the flights crashed.

New York City’s Freedom Tower (Photo Credit: Phil Dolby CC 2.0 via Flckr)

The 9/11 attacks also led to the start of the “Global War on Terrorism,” which continues to this day. The 17-year conflict in Afghanistan, the second longest war in US history, has claimed the lives of 2,372 US military personnel and cost American taxpayers billions of dollars. What’s even more unfortunate is that global terrorism, caused by Al Qaeda offshoots such as ISIS, has only increased since 2001.