15 years ago today, terrorists associated with Al Quaida hijacked 4 jets to crash them into symbols of American power. 2 of the planes crashed into the World Trade Center (the symbol of US economic power), 1 crashed into the Pentagon (the symbol of US military power). In the last airplane (known as "United 93"), somebody in the plane got word that other planes had already crashed into the World Trade Center, so that led the passenger rebellion against the hijackers, which caused the plane to crash into a Pennsylvania field! It was believed that the terrorists were planning to use that airplane into Washington DC!
In the days and weeks following the attack, there was a strong sense of unity & patriotism, more than I had ever seen in my lifetime! People bought American flags, and there was even a flag shortage! I even wore a flag pin for a while, until they kept coming off!
People wanted revenge against the attackers and anyone associated with them! In the US Congress, out of 100 senators and 435 representatives, only 1 voted against military intervention! Very rarely was there that much consensus for anything in Congress!
Overwhelming majorities of US citizens supported US military intervention in Afghanistan to fight against Al Quaida and the Taliban hosting them! Reports of Taliban's cruelty towards its citizens (especially the women) made even the most pacifist of US citizens want the US to take aggressive military action against them.
But as with any strong feelings, they do fade over time!
When President George W Bush wanted to use the US military to overthrow the Iraqi dictator Saddam Hussein (who wasn't involved in the 9/11 attacks, but did want violent revenge against the US for expelling his troops out of Kuwait back in 1991), US unity started to crack! Yes, most of the US Congress (including Hillary Clinton, John Kerry and Joe Biden) voted to support US war against Saddam Hussein, but many left-wing liberals protested against the war (including Bernie Sanders and low-profile Illinois state senator Barack Obama).
President Bush did get re-elected in 2004, but in the following year, his popularity went down the drain as news images showed the lack of quick action taken when Hurricane Katrina hit New Orleans. Being that New Orleans is a black-majority city, it gave the impression that "George Bush doesn't care about black people" as Kanye West stated! Nevermind that Bush hired African-Americans to prominent federal positions including Secretary of State and Secretary of Education.
But the damage to Bush's reputation was done. At the same time, Barack Obama became a political celebrity and many felt that he could be the one who could be the 1st black president of the United States. At the same time, Obama's celebrity (and eventually political victory) scared those who feared he was a "secret Muslim" (his father and step-father were from Muslim-majority countries, but they weren't religious extremist, nor were they a major presence in his everyday life growing up).
While many viewed Obama's victory in 2008 as a healing point where racial tensions would fade, that euphoria didn't last.
Anti-Muslim pundits used social media to fan fears of Obama's plans for America. They claim that Obama wasn't born in Hawaii, and made demands to see his birth certificate, even though it has been shown on Obama's campaign website in 2008!
Donald Trump, a man with no principles, noticed that there was a market that he could take advantage of for his campaign for political office. He exploited fears of the Mexican criminal and the Muslim terrorist to get media attention. He also exploited the fact that many of his Republican opponents were total wusses who couldn't stand their ground when faced with even the most minor of controversies!
At the same time, police brutality against African-Americans were highlighted in social media, bringing the Black Lives Matter movement to life. While the campaign to fight police brutality & racial discrimination is a noble cause, much of that has been overlooked as BLM's tactics (including blocking traffic and screaming in libraries) alienating potential supporters.
To add insult to injury, non-white activists (some of whom were traumatized youth who grew up in mostly white communities) started to plot a shaming campaign against European-Americans by screaming about "cultural appropriation", "microaggressions" (a word I find extremely problematic as explained in this link) and "white privilege". Those activists alienated white allies that would be so willing to listen to minority voices if they were given a chance to contribute their voices too!
So yes, the American unity after 9/11 had faded!
Let's hope it doesn't take another tragedy to bring that unity back to life again!