At the nation's founding, there was one representative per 35,000 people. Now it's one per 700,000. So your voice has dropped 20 times.
Most western democracies have about one national rep per 100,000 people. So again, DC is about 7 times more oligarchic than other nations.
US Constitution, Article I, Section 2 :
"The Number of Representatives shall not exceed one for every thirty Thousand..."
Apportionment Act of 1792 :
"House of Representatives shall be composed of members elected agreeably to a ratio of one member for every thirty-three thousand persons in each state..."
In the original "Bill of Rights" amendments, there was a proposed amendment to cap the rep-per-person ratio to one per 50,000. This amendment was ratified by 11 states by 1792, but it was one state short of inclusion in the Constitution due to growth in the number of states.
Changing the number of reps per capita is as simple as changing the Reapportionment Act of 1929, but obviously incumbents will not vote to dilute their power.