why was it important for the U.S. to have a federal government and what were some of the important facts?

Answer 1

For the Founders there were two important things; commerce and defense.

Before the Federal Government came about, the country operated under the Articles of Confederation (the first constitution). It was more like a United Nations of the states than a real government, it had no real power and it just held the states together in a loose alliance.

Under the Articles each state was charged with its own defense, could print its own money and levy tariffs on goods from other states. However, this led to economic instability and the Founders went back to the drawing board and created the government that exists today. The free transit of commerce across state lines is the ultimate power of the United States, its what makes the United States the single greatest economy in history.

Also, American shipping was under constant threat by European and North African navies and pirates. The country realized that it was vulnerable to invasion and would be stronger under a single central authority rather than 13. The War of 1812 is proof of this.

Answer 2

To make common laws for all the states.
Regulate interstate commerce and enter into treaties with foreign governments.
To conduct all business for the nation with other nations.
Provide a common defense for the country instead of each state deciding if it was going to send the state militia to war or not.
Provide a common currency good in all states,states used to print their own money and money from another state was not always accepted in another state.