Final answer:
The United States' first written constitution was the Articles of Confederation, which was ratified in 1781 but later replaced by the U.S. Constitution due to its limitations.
Step-by-step explanation:
The United States' first written constitution was the Articles of Confederation. This document, drafted in 1777, was ratified in 1781 and marked a key step in the fledgling nation's development. The Articles established a 'firm league of friendship' between the states and outlined the powers of the Confederation Congress, which included the abilities to declare war and conduct foreign affairs. However, it left the Congress powerless to enforce laws, collect taxes, or draft troops without the consent of the states. The limitations of the Articles of Confederation led to their replacement by the United States Constitution in 1789, which created a stronger federal government with an executive, legislative, and judicial branch.