I was born during the first year of the Eisenhower administration. In the 55 years since, our country has been led for 35 years by Republican presidents (64% of that period) and for 20 years by Democratic presidents (36% of the time), a ratio of almost 2:1.
The six Republican presidents during these years were:
Eisenhower 7 years (1954-1960)
Nixon 6 years (1969-1974)
Ford 2 years (1975-1976)
Reagan 8 years (1981-1988)
Bush I 4 years (1989-1992)
Bush II 8 years (2001-2008)
During the same time frame, the Democrats controlled the White House during four administrations:
Kennedy 3 years (1961-1963)
Johnson 5 years (1964-1968)
Carter 4 years (1977-1980)
Clinton 8 years (1993-2000)
Some general observations can be made. Eisenhower and Reagan are usually considered to have had successful tenures in office. Despite being re-elected, Nixon and Bush II are frequently ranked among the worst presidents in American history, and for the same general reason -- their blatant disregard for the legal and constitutional restraints on Executive power. Both Ford and Bush I were defeated for re-election, an obvious indication of the electorate's dissatisfaction with their performance in office.
Among the Democrats, Kennedy and Clinton are commonly viewed as successful, even brilliant, presidents, although Kennedy achieves that ranking more for the promise of his aspirations, goals and moral leadership than for the list of his accomplishments before being assassinated. Johnson, like Nixon and Bush II, won re-election but has his presidency judged more for the failures of his second term in office than for any successes during his abbreviated and emotional first term. Carter failed to win re-election.
As dominant as Democratic administrations were in the first half of the 20th Century (Wilson, Roosevelt and Truman steered the country through three wars and a Depression during a combined 28 years in office), the split was not as dramatically tilted to one party as the 60-40 or 65-35 ratio in favor of Republicans since Eisenhower's election. In fact, it was reasonably close to 50-50 (28 Democratic years to 24 Republican years) as we elected twice as many Republican presidents from 1900-1950 (McKinley, T. Roosevelt, Taft, Harding, Coolidge and Hoover) as Democrats. Of these early 20th Century Republican presidents, only McKinley and T. Roosevelt were re-elected. (McKinley served less than one year of his second term before the assassination and was succeeded by T. Roosevelt.) Moreover, only Teddy Roosevelt among the six Republican presidents in office during the 20th Century before my lifetime is considered to have had a successful presidency.
Needless to say, this is not a great track record. The electorate seems to have missed the mark on presidential elections more often than it hit a winner. In the last 108 years, we have had 12 Republican presidents (11 of whom were elected), and only 3 are considered to have had generally successful terms in office. But we have elected 7 Democratic presidents during that span, and 5 of them are widely regarded as successful.
We give Republicans far more chances at the White House (again trending very close to a 60-40 margin), but the Democrats who have been elected more frequently attain success and accomplishment once in office. Only Lyndon Johnson's sole elected term and Jimmy Carter's lone term have been duds.
I cannot explain what accounts for this disparity along party lines between electoral success and actual results in office. I believe that Barack Obama has a historically-significant opportunity to become a visionary and successful president, a paradigm-shifter, along the lines of FDR, JFK and Bill Clinton. And, frankly, Ronald Reagan fits that description as well, and achieved greatness as president by the same measure. Obama has the vision, judgment, organizational and oratorical skills, and leadership qualities to become a great president in the mold of Roosevelt, Kennedy, Reagan and Clinton. And he has no less governmental experience on a material national and international level than those four great Presidents had when they first ran for that office.
In addition to the goals, policies and programs he proposes, the historical record suggests that Obama has a significant chance for greatness if elected. The country would be best served if the voters gave him that chance in November.