Which president from Andrew Johnson to George W. Bush can be said to have left the boldest mark on American history?

While this is a matter of opinion, I think that a very
strong case can be made that Franklin D. Roosevelt left by far the boldest mark on US
history during this time period.

Roosevelt is famous for
two major things.  He was the creator of the New Deal, which was meant to help end the
Great Depression.  He was also president for the great majority of World War II.  As
such, he presided over the two greatest crises in the last 200 years of American
history.

Roosevelt's strong leadership during WWII did a
great deal to hold the Allied coalition together.  It also did a lot to help ensure that
the war was won.  This is surely something that leaves a "bold mark."  In addition,
Roosevelt is largely responsible for the huge increase in the size and scope of the
national government.  His New Deal, for good or for ill, laid a foundation for the
assumption that the government would deal with all problems faced by the
people.

For these reasons, Franklin Roosevelt is my pick
for the president in this time period who left the "boldest mark" on our
history.