The Constitution's framers intended to alleviate many of the inefficiencies of the Articles of Confederation, but in so doing, they created a system that many felt threatened the sovereignty of the states and the freedom of the American people. Those who favored ratification of the Constitution were known as federalists; those who opposed its ratification were known as anti-federalists.
According to ConstitutionFacts.com, the Constitution solved many of the problems that plagued the country under the Articles of Confederation. For instance, the Constitution established fair representation in the legislature by creating a House of Representatives based on state population. The Constitution also established a national court system, and empowered Congress to impose taxes to make it easier for the national government to take care of the country's needs.
ConstitutionFacts.com states that the primary concern of the anti-federalists was the Constitution's perceived threat to liberty. The Constitution set up a strong central government similar to the British system from which Americans had just escaped. Ratification would seemingly place the states at the mercy of a distant, unsympathetic national government. Furthermore, the Constitution did not include a bill of rights that many anti-federalists believed was essential to protecting the liberty of the people. This concern led to the adoption of the Bill of Rights as amendments to the ratified Constitution.