In what ways did the power of the American government expand as a result of WW1?

The major
expansion of American government power was directed at the war effort; not at long time changes
in governmental policy. The Lever Food and Control Act created the U.S. Food Administration to
garner resources for the war effort. Under the leadership of future President Herbert Hoover,
the Food Administration urged Americans to observe meatless Tuesdays; wheatless Wednesdays, and
porkless Saturdays. The Espionage Act of 1917 provided penalties of up to twenty years for
interfering with the war effort, or inciting insubordination, disloyalty, or  refusal to serve
in the armed services.  Similarly, the Sedition Act of 1918 made it illegal to interfere with
the sale of war bonds, or say or write anything,

disloyal,
profane, scurrilous, or abusive about the American Government, Constitution, Army, or
Navy.

Among those prosecuted and convicted under the
Sedition Act was Eugene V. Debs who famously stated he was against all wars except one, and that
was the worldwide worker's revolution.

It is highly doubtful that the two
acts cited above would stand Constitutional muster during the present; however they were
challenged and upheld by the Supreme Court in the case of Schenk vs. U.S.in
which Chief Justice Oliver Wendell Holmes wrote:

The most
stringent protection of free speech would not protect a man in falsely shouting fire in a
theater and causing a panic .

The Court held in the
Schenk case that the First Amendment did not apply when there was a
"clear and present danger" of evil results.