As of 2015, there have been 44 presidents in the history of the United States. The first president was George Washington, elected in 1789. After two terms in office, he was followed by John Adams, Thomas Jefferson, James Madison and then James Monroe.
Following President Monroe, John Adams son, John Quincy Adams became president. Following Adams were Andrew Jackson, Martin Van Buren and William Henry Harrison. Next were John Tyler, James K. Polk, Zachary Taylor and Millard Fillmore. Franklin Pierce and James Buchanan came next as the country was on the verge of Civil War. Abraham Lincoln was elected president just before the South officially seceded from the union. After Lincoln's assassination in 1865, Andrew Johnson, Ulysses S. Grant, Rutherford B. Hayes and James Garfield were presidents. The final four presidents of the United States in the 19th Century were Chester A. Arthur, Grover Cleveland, Benjamin Harrison and then Cleveland for one more term. Cleveland's terms in office count as two separate presidencies.
William McKinley was elected in 1900, but he was assassinated, and Theodore Roosevelt took his place. Roosevelt was followed by William H. Taft, Woodrow Wilson, Warren G. Harding and Calvin Coolidge. Herbert Hoover followed, but after the stock market crash of 1929, Hoover would not see another term, as Franklin D. Roosevelt would be president and stay in office for almost four straight terms. After Roosevelt's death in 1945 during his final term, Harry S. Truman became president, followed by Dwight D. Eisenhower, John F. Kennedy, Lyndon B. Johnson and Richard Nixon. Gerald Ford, Jimmy Carter, Ronald Reagan and George H. W. Bush followed Nixon. Next were William J. Clinton and George W. Bush, and the president as of January 2015 is Barack Obama.