
Bush's presidency did not begin on the strongest footing. Many people were unconvinced that he had even won the 2000 election. When the election returns were tallied on November 7, nobody was sure who had won the election, as the results in the decisive state of Florida necessitated a recount. The initial recount also went to Bush, but the outcome was tied up in lower courts for a month until eventually reaching the U.S. Supreme Court. On December 9, in a controversial ruling, the Court reversed a Florida Supreme Court decision that had ordered a third count, and stopped an ordered statewide hand recount. The machine recount showed that Bush had won the Florida vote by a margin of 537 votes out of six million cast. This meant that Bush won the election, receiving 271 electoral votes to 266 for his opponent Al Gore.
The turning point in Bush's Presidency occurred on September 11, 2001. Four coordinated terrorist attacks were perpetrated by the Islamic terrorist group al-Qaeda. The attacks killed 2,996 people, injured over 6,000 others, and caused at least $10 billion damage. Four passenger airliners operated by two major U.S. passenger air carriers were hijacked by 19 al-Qaeda terrorists. Two of the planes, American Airlines Flight 11 and United Airlines Flight 175, were crashed into the North and South towers of the World Trade Center complex in New York City. Within an hour and 42 minutes, both 110-story towers collapsed, with debris and the resulting fires causing partial or complete collapse of all other buildings in the World Trade Center complex. A third plane, American Airlines Flight 77, was crashed into the Pentagon. The fourth plane, United Airlines Flight 93, was initially steered toward Washington, D.C., but crashed into a field in Stonycreek Township near Shanksville, Pennsylvania, after its passengers tried to overcome the hijackers.
That evening, President Bush addressed the nation from the Oval Office. He promising a strong response to the attacks and stressed the need for national unity and support the families of the victims. Three days after the attacks, Bush visited Ground Zero and met with Mayor Rudy Giuliani, firefighters, police officers, and volunteers. He addressed a group of workers using a megaphone while standing in a heap of rubble. When someone from the crowd told Bush "I can't hear you", he responded: "I can hear you. The rest of the world hears you. And the people who knocked these buildings down will hear all of us soon."
In a September 20 speech, Bush condemned Osama bin Laden and his organization Al-Qaeda, and issued an ultimatum to the Taliban regime in Afghanistan, where bin Laden was operating, to "hand over the terrorists, or share in their fate". He also declared what became known as the Bush Doctrine, declaring that anyone who harbored, aided or abetted the terrorists would also be considered to be an enemy of the United States. He announced the commencement of the War on Terror, beginning with the invasion of Afghanistan to depose the Taliban, which had harbored al-Qaeda. Many countries strengthened their anti-terrorism legislation and expanded the powers of law enforcement and intelligence agencies to prevent terrorist attacks. Following the attacks, President Bush's approval rating soared to 90%
The destruction of the World Trade Center and had a significant effect on global markets, resulting in the closing of Wall Street until September 17. Commercial air travel was grounded in the U.S. and Canada until September 13. Cleanup of the World Trade Center site continued until May of 2002, and the Pentagon was repaired within a year.

The war in Afghanistan in 2001 was followed by the Iraq War in 2003. Bush was able to bring about significant legislative changes including broad tax cuts, the Patriot Act, the No Child Left Behind Act, the Partial-Birth Abortion Ban Act, Medicare prescription drug benefits for seniors, and funding for the AIDS relief program known as PEPFAR. In the 2004 Presidential race, Bush defeated Democratic Senator John Kerry by a greater margin than he his victory in 2000. But he received increasingly criticism for his handling of the Iraq War, and his response to Hurricane Katrina. His popularity declined as the Democratic Party regained control of Congress in the 2006 elections.
In December 2007, the United States entered its longest post-World War II recession, often referred to as the "Great Recession". Bush took office during a period of economic recession. The dot-com bubble had burst and the terrorist attacks also adversely impacted the economy. Fighting two wars had increased federal government spending from $1.789 trillion to $2.983 trillion. Revenues also increased from $2.025 trillion to $2.524 trillion (from 2000 to 2008), but this not keep pace with spending. Defense spending was increased by 107 percent, and spending in most other areas also increased. The increase in spending was more than under any predecessor since Lyndon Johnson.
Bush had entered office following three straight years of fiscal surplus. The surplus in fiscal year 2000 was $237 billion, the largest surplus ever. Bush felt that unspent government funds should be returned to taxpayers. He said "the surplus is not the government's money. The surplus is the people's money." Federal Reserve chairman Alan Greenspan disagreed, and warned of a recession. Treasury Secretary Paul H. O'Neill opposed tax cuts because he believed that they would contribute to budget deficits and undermine Social Security.
During the 2001 to 2008 years, GDP grew at an average annual rate of 2.125 percent, a slower rate of growth than in previous years. Unemployment originally rose from 4.2 percent in January 2001 to 6.3 percent in June 2003, but subsequently dropped to 4.5 percent by July 2007. By the end of the Bush presidency, the unemployment rate rose to 7.2%. Adjusted for inflation, median household income dropped by $1,175 between 2000 and 2007 and the poverty rate increased from 11.3 percent in 2000 to 12.3 percent in 2006 after peaking at 12.7 percent in 2004. By October 2008, the national debt had risen to $11.3 trillion, from $5.6 trillion when Bush became president.
In December 2007, the United States entered the recession since the Roosevelt administration. It came with a housing market correction, a subprime mortgage crisis, rising oil prices, and a declining dollar. In February of 2008, 63,000 jobs were lost, a five-year record. To address the situation, Bush signed a $170 billion economic stimulus package which was intended to improve the economic situation by sending tax rebate checks to many Americans and providing tax breaks for struggling businesses. In September 2008, the crisis became much more serious beginning with the government takeover of the Federal National Mortgage Association, commonly known as "Fannie Mae" and the Federal Home Loan Mortgage Corporation, better known as Freddie Mac. This was followed by the collapse of Lehman Brothers and a federal bailout of American International Group for $85 billion.
This was considered to be the worst financial crisis since the Great Depression. Bush, meanwhile, proposed a financial rescue plan to buy back a large portion of the U.S. mortgage market. By November 2008, over 500,000 jobs were lost, which marked the largest loss of jobs in the United States in 34 years. The Bureau of Labor Statistics reported that in the last four months of 2008, 1.9 million jobs were lost. By the end of 2008, the U.S. had lost a total of 2.6 million jobs.
Many Americans blamed their president. Bush's approval rating fell to a low point of 25% in three separate approval ratings polls taken in October and November of 2008. Other pollsters had Bush's approval rating as low as 19%. Bush's lack of popularity was visited upon the man who succeeded him as the Republican candidate for President, Senator John McCain. The once popular McCain was soundly defeated in the election of 2008 by Barack Obama by a margin of 365 to 173 in the electoral college.

In February 2012, Gallup reported that "Americans still rate George W. Bush among the worst presidents, though their views have become more positive in the three years since he left office. Bush's favorability ratings in public opinion surveys had begun to rise a year after he had left office, from 40 percent in January 2009 to 45 percent in July 2010. In April 2013, Bush's approval rating stood at 47 percent approval and 50 percent disapproval in a poll jointly conducted for The Washington Post and ABC, his highest approval rating since December 2005. His approval ratings are often compared with those of Harry Truman, a man who left office despised, only to have his reputation experience a rehabilitation decades after leaving office.