The time period between 1781 and 1789 is often referred to as the "Critical Period", and with a good reason. As a newly formed country America had a lot to lose if it did not survive and prove its self to the world as well as the citizens. Going into the critical period the United States was run under the Articles of Confederation but the lack of a centralized government soon proved the articles to be inept.
The Problems with the Articles appeared almost upon completion. The fact that full state approval was needed to pass any official proclamation meant that congress never had any real power. Such was the case when in 1783 the Rhode Island Assembly refused to place any taxes on imported goods. Because congress wasn't given any power to enforce the laws only "suggest" states enforce them the economy as well as national unity suffered.
The power to tax was crucial power needed by the government.
Under the Articles of Confederation the US economy was extremely fragile having just emerged from depression. The market value would jump thousands of dollars one year and fall the next. The power to tax was needed to help stabilize the volatile market.
The government also needed to be centralized in order to prove to other countries they were united. Proving to be unified would allow them more leverage when dealing with foreign policies. In a speech made to congress John Jay told of negotiations with Spain's Minister, Diego de Gardoqui in which Spain denied the US navigation of the Mississippi River because he didn't see the US as unified and knew there was nothing the US could do about it. The government also needed the power to create treaties and alliances, this was extremely important in the survival of the...