Earlier this month, NPR asked "Is American Democracy Sliding Toward Minority Rule?" I'm guessing that was a rhetorical question. As the late John Prine sang, "a question ain't really a question if you know the answer too."
I think the short answer is, we always have been (the same can be said of any class society)...but things are getting worse. For starters, as Princeton researchers reported years ago, with growing inequality and the power of money (not to mention Citizens United), the US is more an oligarchy than a democracy.
However, the NPR story was more about politics as usual than political economy. The Constitution mandates that each state be represented by two senators, no matter how small, although it was adopted prior to the formation of formal political parties.
Today, that means that while the Senate is evenly divided by party, Democratic senators represent 41.5 million more Americans than their Republican counterparts. If these trends continue, by 2040, 70 percent of Americans will be represented by 30 percent of senators and vice versa.
(Then there's the whole thing about places like the District of Columbia and Puerto Rico being denied statehood and representation...and I'm not even going to mention the electoral college.)
Add to that the fact that with the filibuster, 40 percent counts for more than 60 percent. Add the numbers above and it's clear we have a problem that's only going to get worse in times to come.
Something has to give.