Sept. 8 (UPI) -- In many ways, witnessing the unprecedented terrorist attacks on Sept. 11, 2001, might seem like it wasn't terribly long ago -- and in other ways, it may feel like it's really been two decades. Regardless, many changes have occurred in that time that are direct results of 9/11.
Trying to imagine how life and the world were before that day could take some degree of effort. That in and of itself is a reflection of just how much has changed over the past 20 years.
Here is a look at 20 ways that the attacks altered the United States, our lives and our world in the decades since:
War in Afghanistan
Then-President George W. Bush declared a global "War on Terror" shortly after the attacks, and the United States and Britain conducted airstrikes targeting Taliban and al-Qaida training camps on Oct. 7, 2001.
The campaign in Afghanistan fluctuated in intensity over the past two decades and resulted in more than 70,000 deaths, including 2,400 American troops.
A week ago, the U.S. military completed its withdrawal from the Middle Eastern nation and the last C-17 aircraft carrying Americans and vulnerable Afghan aides departed.
War in Iraq
Bush quickly turned to Iraq as the next step in the war on terror.
U.S. and coalition forces invaded Iraq on March 19, 2003, citing intelligence that the country and its leader Saddam Hussein possessed or were working to develop weapons of mass destruction.
Bush declared "Mission Accomplished" on May 1, 2003, in a speech aboard the USS Abraham Lincoln. In December 2011, then-U.S. Defense Secretary Leon Panetta declared the end of combat and the formal end of the war and the recognition of an "independent, free and sovereign Iraq."
The fighting lasted for eight years and killed 25,000, including 4,500 U.S. personnel.
Before Sept. 11, security at all U.S. airports was handled by private security firms. In the weeks and months that followed, the federal government took over all aspects of airport security -- a measure intended to prevent anything like 9/11 from happening again.
In late 2001, Bush signed the Aviation and Transportation Security Act and formally established the Transportation Security Administration -- an agency that, to this day, has the final word over all security matters related to commercial air travel.
Many reforms included requiring more federal air marshals on domestic flights and strengthening cockpit security. There were also new regulations that barred all but ticketed passengers from venturing beyond security checkpoints.
When you remove your shoes and put your laptop in a security bin at an airport, it's a direct result of 9/11.
The National Commission on Terrorist Attacks Upon the United States, or the 9/11 Commission, was established by Congress in 2002 with the purpose of assembling "a full account of the circumstances surrounding" the Sept. 11 attacks.
In its final report, the commission found that the CIA and FBI failed to detect the plot -- and said the attacks might have been averted had they acted more wisely and aggressively.
Earlier this year, House Speaker Nancy Pelosi proposed a similar style of commission to investigate the Jan. 6 attack at the U.S. Capitol.
Homeland Security Dept. created
On Feb. 28, 2003, Bush transferred 170,000 employees from 20 federal agencies to create the Department of Homeland Security, marking the largest reorganization of federal agencies since President Harry Truman placed the government's intelligence operations under the control of the Central Intelligence Agency in 1947.
The agency's stated purpose is to secure the nation's air, land, sea and borders "to prevent future attacks against the United States."
DHS is now the nation's chief security agency, employs about 240,000 people and is the third-largest Cabinet department.
Saddam Hussein executed
The longtime Iraqi dictator was captured in a hole in the ground near his hometown of Tikrit on Dec. 14, 2003, ending an eight-month manhunt that began after coalition forces took Baghdad.
Three years later, Hussein his half-brother and former intelligence chief Barzan Hassan and former Chief Judge of the Revolutionary Court Awad Bandar were sentenced to death for crimes against humanity. Hussein was hanged on Dec. 30, 2006.
Abu Ghraib Torture
In 2004, a report detailed physical abuse and sexual degradation of Iraqi prisoners and the killing of Manadel al-Jamadi in Abu Ghraib prison in Iraq during the U.S. occupation.
The United States removed 17 soldiers and officers from duty and 11 were charged with dereliction of duty, maltreatment, aggravated assault and battery for their involvement. Congress in 2005 passed the Detainee Treatment Act that banned "cruel, inhumane, or degrading treatment" of prisoners held in U.S. custody.
The Iraqi government closed the prison in 2014 amid fears it could be overrun by Sunni insurgents.
In 2019, former President Donald Trump and Taliban leaders reached an agreement to withdraw the 14,000 U.S. troops who remained in Afghanistan. The deal stipulated that the Afghan government work to have Taliban members removed from the U.N. Security Council's sanctions list and that the United States must refrain from using force against the territorial integrity of Afghanistan and interfering in domestic affairs.
Then-acting Secretary of Defense Christopher Miller announced last fall that the United States would withdraw an additional 2,500 troops by Jan. 15. Trump had wanted all troops out of Afghanistan by May 1.
Osama bin Laden killed
On May 1, 2011, then-President Barack Obama announced that U.S. special forces had killed Osama bin Laden, the founder of al-Qaida and the world's most wanted terrorist leader.
Bin Laden declared war against the United States in the 1990s and was the chief force behind 9/11. Bin Laden escaped the U.S. manhunt for nearly a full decade before a special operation closed in on him at a private compound in Pakistan.
In the wake of the U.S. withdrawal in Afghanistan, Biden said the chief U.S. interest in Afghanistan was killing bin Laden and dismantling al-Qaida.
Five prisoners at Guantanamo Bay are still awaiting trial at the naval base in Cuba for aiding the men who conducted the Sept. 11 attacks, including accused mastermind Khalid Sheik Mohammed.
They face charges including conspiracy, murder in violation of the law of war and terrorism. Since 2012, the case has faced multiple setbacks and delays, partly due to the COVID-19 pandemic.
Obama ran on a promise to close the Guantanamo base, but never did. The base has been a hotbed of controversy virtually from the first day terrorist detainees were taken there and interrogated.
The Homeland Security Act of 2002 also created U.S. Immigration and Customs Enforcement, Citizenship and Immigration Services and Customs and Border Protection, which aligned with an increase in deportations in the wake of 9/11.
Deportations and voluntary departures nearly doubled from 2001 to 2011, while criminal deportations increased by about 400% from 18,000 in 2001 to 91,000 in 2012, according to a 2012 ABC News report.
War powers shift toward Executive Branch
In the wake of the attacks, Congress and President Bush implemented two measures that authorized of use of military force by the executive branch.
The first, passed days after Sept. 11, granted the president authorization to target "nations, organizations or persons he determines planned, authorized, committed or aided the terrorist attacks," and the second granted authorization for military operations in Iraq.
Obama cited the measure when conducting airstrikes against Libya in 2016, and Trump drew on the change to justify U.S. forces killing Iranian Gen. Qassem Soleimani in 2020.
Patriot Act signed
Six weeks after Sept. 11, Congress passed the Patriot Act, which granted the federal government more powers to conduct surveillance inside the United States.
The law included provisions that allowed law enforcement to use wiretapping to investigate terror-related crimes and allowed federal agents to seek federal court permission to obtain bank records to aid national security terrorism investigations.
The highly controversial law was renewed multiple times and officially expired in 2015. Some key provisions, however, continue via other federal laws.
FISA Amendments Act
In 2008, Bush signed a law amending the Foreign Intelligence Surveillance Act of 1978 that greatly expanded the government's ability to conduct physical and electronic surveillance.
The law gave immunity to telecommunication companies that cooperated with the National Security Agency in electronic surveillance, increased the length of time allotted for warrantless surveillance and provided a provision that allowed emergency eavesdropping.
In 2015, Obama signed the USA Freedom Act, which forced the NSA to stop its collection of phone "metadata" -- which includes a phone call's length and the number called, but not the content of the call.
9/11 Victims Fund
Shortly after the attacks, Congress established the September 11th Victim Compensation Fund to provide aid to families of those killed and casualties of the attacks.
The fund first operated from 2001 to 2004 and was reactivated in 2011. Some 40,000 people had applied to the fund, with 20,000 claims pending by 2019, when Trump signed a measure securing funds for the program through 2090.
Greater defense budgeting
The federal government spent an estimated $2 trillion between 2001 and 2019 in emergency funding to support the response to the Sept. 11 attacks, amounting to 9.5% of total discretionary spending during the period, according to the Congressional Research Service.
The funds are not subject to discretionary spending limits established in 2011. However, Congress and the president are required to designate funding on an account-by-account basis.
Congress also used the funds to upgrade Capitol security, including increasing the size of the U.S. Capitol Police force by 27% and combining the forces of the Capitol Police and the Library of Congress.
Other reforms expedited in the wake of 9/11 include upgrading the Capitol Visitors' Center to serve as a security screening point for visitors, closing streets surrounding congressional office buildings and constructing additional vehicle barriers.
The U.S. Capitol was believed to be the target of the hijackers on United Airlines Flight 93, which crashed in Pennsylvania after a passenger revolt.
Anti-Muslim hate crimes
Hate crimes against Muslims skyrocketed from 28 in 2000 to 481 in 2001 after the attacks. They also went from being the least reported among religious-bias incidents to the second-highest, according to FBI data.
Numbers declined in the following years, but have never returned to pre-9/11 levels. In 2016, assaults against Muslims rose to 127, surpassing the peak of 93 in 2001.
Patriotic sentiment increased dramatically after 9/11, with almost 80% of adults saying they had displayed an American flag in the weeks after Sept. 11. About 62% said a year later that they felt patriotic as a result of the attacks, according to Pew Research.
Pew found that people also turned to faith, with 78% of people saying the influence of religion in American life was increasing, Many said they prayed more often in the days and weeks after 9/11.
New World Trade Center
For years after 9/11, there was constant speculation, proposals and planning to build a replacement for the destroyed World Trade Center. It wasn't until 13 years later that the primary replacement skyscraper, One World Trade Center, finally opened.
On Nov. 3, 2014, the first tenants moved into the tower, which was built on the former site of the original 6 World Trade Center. Also called the Freedom Tower, the building has 104 stories and stands 1,776 feet tall. Construction cost $3.9 billion, twice the original estimate.
The new World Trade Center site also contains the National 9/11 Memorial, which features two reflecting pools in the footprints of the former Twin Towers.
The new tower underwent a number of style revisions in the years after the original towers were destroyed.
20 years of mourning: 9/11 terrorist attacks on America