Is the US an oligarchy?

I would love to hear your thoughts.

It seems like America is slowly becoming more class conscious. More people, Trump supporters seemingly included, realize a small group of wealthy elites and corporations hold a lot of power over both our economy and politics. From what I hear from trump supporters they seem to realize the wealth gap is huge, monopolies exist, money is entrenched in politics (especially after citizens united), etc. So would you say an oligarchy a relatively fair way to describe the current state of America, or do you think the system is still fair and representative of the people?

I’m also asking this because Trump promised to drain the swamp, but it feels like he’s only taken the mask off to reveal the true swamp—and he hadn’t really done much to drain it. Jeff Bezos, Mark Zuckerberg, Rupert Murdoch, Bill Gates, and others have seem to rally around trump. Does this concern you at all?