Why did the Framers of the Constitution create a bicameral legislature?
After seven weeks of hard work during the summer of 1787, the Constitutional Conventional was in serious jeopardy of concluding without a document that would replace the ineffective Articles of Confederation. Delegates of the convention were threatening to withdraw from the proceedings if their voices were not heard on one important issue. This issue was fiercely debated for two weeks and had polarized the delegates to the point of frustration. The issue at stake was the apportionment of members to the legislative branch of the newly formed United States. The parties at odds were delegates of less populated states and those from states with robust populations.
The smaller states insisted that representation in the legislative branch have equal suffrage for each state. They felt that larger states would become tyrannical and abuse their advantage at the cost of small states. The plan they proposed was known as the New Jersey Plan.
The heavily populated states, on the other hand, felt that they would be contributing more revenue for the maintenance of the nation and should have more representation than smaller states. Their plan, the Virginia Plan, would base representation in the houses of Congress entirely on population.
With the future of the convention in a tenuous position, it was decided that a committee needed to be established to arrive at a compromise. As a result of the committee proceedings, Roger Sherman and Oliver Ellsworth drafted a brilliant solution that would be called the Connecticut Compromise. Their proposal would allow for apportionment to the lower house be dependent on the population of the states while the upper house would have equal representation per state. To further assuage the concerns of the smaller states, further concessions were made in terms of the powers the lower house would be granted. As an example, spending and revenue bills are proposed by the lower house and cannot be amended by the upper house.
The Connecticut Compromise, or the Great Compromise of 1787, effectively saved the Constitutional Convention. While a bicameral legislature in itself offers countless benefits in terms of separating powers, the Founding Fathers chose this route to allow convention proceedings to continue. This allowed for the ultimate intent of the Convention: the creation of a more perfect union.
This method also was meant to balance the powers of geography, population, and what I would call the big picture and the little picture.
In the House, representation is based upon population in a fairly small geographical area, ensuring that there are people who are expected to represent the interests of their "local" communities. With a certain limited number of people from one small geographical area to represent, it was thought that these representatives would better reflect the local interests. This also had the effect of diluting the influence of more highly populated states, since each district is made up of approximately the same number of people. A Congressman from a district in Texas has no more or less power than a Congressman from New Hampshire.
The Senate, on the other hand, smooths out the differences in population and geography, giving each state equal power in decision-making, no matter how many people are in the state and no matter how large or small the state is geographically. Thus in the Senate, California and Vermont have equal representation. At least theoretically, each senator is expected to have more of a big picture in mind, considering the people of the entire state and considering the nation as a whole.
This was a well thought out plan, in spite of the fact that we have been experiencing so much gridlock in recent years. And I am not aware of any government in the world that has worked out a better way to set up a government.
The Framers of the Constitution created a bicameral legislature as part of their efforts to create separation of powers and to, more generally, make it harder for the government to do anything.
The Framers were very concerned about the ability of the government to tyrannize the people. They worried that a government that could act easily would get caught up in popular passions and make decisions that would either be tyrannical or simply bad for the country. In order to make it less likely that the government would act so quickly and "badly" the Framers created a bicameral legislature. Such a legislature would make it harder for any law to pass because proposed laws would have to pass both houses, which would have different constituencies and terms of different lengths.
In short, then, the point of this was to make government less efficient and, therefore, less dangerous.