How has the United States' fiscal policy changed over the last century?

This is a pretty broad question.  I would say that there
are two important ways to answer it.

First, fiscal policy
is much more Keynesian today than it was in 1910.  This change started with the New Deal
and has continued on, more or less unchanged, to the present.  Nowadays, the federal
government tends to believe in using spending and/or tax cuts to try to stimulate the
economy (as happened late in the Bush and early in the Obama
administrations).

Second, I would say that there is simply
more fiscal policy now.  In other words, the government does much more taxing and
spending than it did in 1910.  It involves itself much more in the economy than it did
in those days.  This, too, started with the New Deal and
continued.