When and where were the most past, present and future US Presidents
all gathered in one place at the same time?  Was it JFK's Inaugural ?
(Truman, Ike, JFK, LBJ, Nixon and then Congressman Ford were all in
attendance).

There have never been more than six Presidents/Former Presidents
living at any one time. These were:

3/4/1861 1/18/1862
LINCOLN, BUCHANAN, PIERCE, FILLMORE, TYLER, VAN BUREN

1/20/1993 4/22/94
CLINTON, G.H.W. BUSH, REAGAN, CARTER, FORD, NIXON

1/20/01 to 6/5/04
G.W. BUSH, CLINTON,  G.H.W. BUSH,  REAGAN, CARTER, FORD


PRESIDENT AND FORMER PRESIDENT OF THE U.S. TIMELINE
http://home.mn.rr.com/wagger/Presidents_of_U.S.html

Benjamin Harrison, Chester A. Arthur, Rutherford B. Hayes, & James A.
Garfield all future presidents at the time, attended Lincolns
inauguration in 1860.

INTERESTING FACTS
http://members.tripod.com/goklassen/websectors/facts/factint.htm

Five Presidents attended Former President Ronald Reagan?s funeral:
George HW Bush, Jimmy Carter, Gerald Ford, Bill Clinton and George W
Bush. As history will undoubtedly note at some point, there was more
then likely a future President in their midst.

On a much broader scale, the most future Presidents ever to assemble
for a single event was seven (eight, if you count the present
President, Franklin Roosevelt), and that event was World War II:

Dwight Eisenhower, John Kennedy, Lyndon Johnson, Richard Nixon, Gerald Ford, 
Jimmy Carter, George HW Bush

Please let me know if this answers your question.

Tutuzdad-ga

Do you know if Buchanan was also at Lincoln's inauguration.  Again I'm
looking to see if there was some time in history where more than six
past current and future presidents were assembled.  Founding fathers,
perhaps?

Thansk.

I'm confused. Now you are asking about a time when "more than six"
were together at one time. Is there a specific event you'd like to
have researchered?

tutuzdad-ga

Add two more names to the the list of WWII era presidents: FDR, his VP
Truman, Ike (Army), JFK (Navy), LBJ (Navy), Nixon (Navy), Ford (Navy),
Reagan (Army) and GHW Bush (Navy)for a total of NINE all involved in
WWII.