The death of President John F. Kennedy 25 years ago is being relived by the media.

There are extravaganzas of the murder in Dallas, what-if pieces and more conspiracy theories than you can shake a stick at.For me, it is all very depressing - thinking about what could have been if Kennedy had not been assassinated.

Of course, when great and powerful men and women are taken from us, history is changed. And who can say for sure what would have happened?

It is clear that the face of American politics was changed - and I believe, changed for the worst - for years to come.

Consider this:

Kennedy's death brought Lyndon Johnson to the presidency. Johnson brought us the Vietnam War - in my opinion the greatest foreign policy mistake in United States history.

No one can say for sure what Kennedy would have done with the Vietnam conflict. He did increase America's military commitment to the country.

But he also said a number of times that the war had to be fought by the South Vietnamese, that the U.S. could only provide military aid and advisors. I'd like to think me meant that, and that he wouldn't have committed large numbers of U.S. combat troops as Johnson did.

In any case, Johnson listened to the military leaders who said the war could be won if only more men and material were sent.

The unpopular war proved to be Johnson's political undoing.

After a landslide victory in 1964 against then-Sen. Barry Goldwater, who advocated a strong military stand throughout the world, Johnson realized that he couldn't win re-election in 1968.

His bombing of North Vietnam and other war policies were so unpopular that Americans voted for a change - voted for Richard Nixon.

Nixon's political career went downhill fast after he lost to Kennedy in 1960 and without the Vietnam War as the main issue of the day, it's unlikely Nixon could have won the White House in 1968.

Nixon, of course, gave us the Watergate scandal during the 1972 election. If Gerald Ford hadn't pardoned Nixon, then Nixon surely would have gone to prison for obstruction of justice and other crimes.

Americans' trust in the federal government was severely shaken by the scandal. And they turned to Jimmy Carter in 1976 - a man who won the highest office in the land by simply promising not to lie to the people. That in itself shows the disillusionment of voters.

But Carter wasn't a strong president. He and his minions seemed to stumble through the next four years.

When Carter allowed the dethroned Shah of Iran into the U.S. for medical treatment, Iranians took U.S. diplomats hostage in Tehran. The failed hostage rescue attempt by U.S. forces sealed Carter's political fate.

America, again, wanted new leadership and opted for Ronald Reagan.

So, in an almost direct line of cause-and-effect, Kennedy's death led to Johnson, whose failed war policy led to Nixon, whose corruption led to Carter, whose ineptness led to Reagan.

Reagan was the first U.S. president to serve two full terms since Ike Eisenhower left office almost 30 years ago.

If you discount Johnson's 1964 victory as a vote for the memory of the beloved Kennedy, George Bush was the first candidate of the same party as the previous administration to win the presidency since Harry Truman's 1948 win.

John Kennedy's death has greatly affected our lives over the last 25 years. Leaving us to wonder this week, what if . . .