"The
world needs to be reminded that all human ills are not curable by legislation."
Warren G. Harding, U.S. President, 1921-1923
While President Harding believed that all human problems couldn't not be solved by more laws, the first part of the 1920's saw laws go into affect that would change the face of the nation throughout the twenties. In addition the growth of big business and the defense of the "American" way of life moved politics into the shaky ground that threaten the very democracy they hoped to protect.
While Harding started out the Twenties on a high note he was soon dealing with a major political scandal - The Teapot Dome Scandal. http://gi.grolier.com/presidents/ea/side/teapot.html
Calvin Coolidge who was the vice-president under Harding became President in 1923. WHY?
Coolidge was careful to make sure no scandals broke out during his administration,
though 
he did continue Harding tradition of what many considered favoring
big business.
"The business of America is business." President Coolidge
But outside of his dealings with big business President Coolidge was nothing like his predecessor.
Coolidge represented in his own person many of the virtues of traditional New England. He was pithy, terse, upright, and honest. He kept his word and expected other people to keep theirs. He didn't speak unless he had something to say, and then he was always specific and to the point. All these classic virtues were appreciated by the general public. In many ways he was the perfect President in an era when people were intent on pursuing their own futures, disillusioned with large internationalist ideals, and uninterested in large governmental enterprises.
But there was also a sour side to Calvin Coolidge
that led him to be disliked by some who saw him when out of the public
eye. Longtime
White House usher
Irwin Hoover, who had adored working for Woodrow Wilson and others, wrote, "President
Coolidge was different from the rest. He seemed to be always watching,
suspicious lest something be 'put over' on him." Even his humor had a
terseness to it. Once, a dinner partner told him she had made a bet she could
engage
him in conversation for five minutes. His answer consisted of two words: "You
lose." When asked why he attended so many luncheons and dinners, he offered
the more expansive, "Gotta eat somewhere." And when someone once
requested a new photograph of him, he said slyly, "I don't know what
you want another for; I'm using the same face." And then there was tragedy,
stark tragedy, in the sudden death of his younger son, Calvin. Coolidge
blamed himself for it: "If I had not been President he would not have
raised a blister on his toe . . . playing lawn tennis on the South grounds
. .
. which resulted in blood poisoning. . . . When he went, the power and
the glory
of the Presidency went with him." [From Philip Kunhardt Jr., et. al.,
The American President (New York: Riverhead Books, 1999), pp. 272-281).]
After World War I America was recognized as a world power and Americans tried to protect their way of life. Unfortunately some of their attempts became serious threats to democracy. The Red Scare was a time of panic in America in 1919. Red was a symbol of communism. Americans feared Communists might win control of the United States. The government arrested thousands of people who they thought might be Communist or anarchists. This "fear" of the unknown led to the creation of one organization that still exist today and a court case that will forever stand as what happens when fear of foreigners take hold of a country.
In 1918, Congress passed the 18th Amendment to the Constitution, prohibiting the manufacture, transportation, and sale of alcoholic beverages. States ratified the Amendment the next year. This movement was known as prohibition.
Herbert Hoover, U.S. President 1929-1933, called prohibition
a "noble
experiment," but
the effort to regulate people's behavior soon ran into trouble. Enforcement
of prohibition 
became
very difficult. Soon, such terms as "bootlegger," "bath
tub gin," and "speakeasy" became household words. Gangs of
hoodlums became more powerful as they trafficked
in alcohol. Hoover won because Coolidge decided he did not want to run in
1928. Hoover ran promising that Americans would continue to enjoy prosperity.