The United States long ago ceased to be anything resembling the republic the Founders envisioned. When the Constitution was ratified there 30,000 people for every representative in Congress, and for many of the Founders, like George Mason who spearheaded the drive for a bill of rights, this number still seemed high. But now with over 300 million people in the country, and the number of representatives capped at 435 there are almost 700,000 people for every representative in Congress–a number that will continue to grow. It may be absurd to believe that one person can represent 30,000, but that just makes it all the more absurd to believe one can represent 23 times that much. It is the equivalent of six people representing the entirety of the American population at the time of the Constitution’s ratification.
We can only restore the level of representation circa 1790 in two ways: expanding the number of representatives from 435 to just over 10,000 or by dividing the country up into smaller polities. The first option raises the obvious question of how an organization of 10,000 could function and where they could meet, but it would also make each representative’s power negligible in exact proportion to how much it would strengthen each citizen’s power to influence her representative, making the whole point moot.
"Representation" itself is something with which a lot of people have a problem. Montesquieu discusses this in the context of a state which has gotten too large. He says that a republic which becomes too large will die due to a thousand special interests. What he means is that special interests will accumulate power to the detriment of the general population, including the representation of the political body. Representatives start representing the interests of those who fund their re-election campaigns.
Originally, the Senate dealt with this by ensuring that special interests could not become centralized, but a couple of minor faults were exploited in order to create the 17th Amendment, which allowed powerful interests to control both houses of Congress, and unleashed central government growth. The only way the government can be limited again is to repeal the 17th Amendment.