In your opinion, when did our elected representatives stop representing the American People?

It has happened over time as the special interest groups have given more and more money and drown out the voice of the American citizen

In my personal opinion, Clinton's second term. I think not impeaching him after a public affair and Hillary playing "stand by your man" just threw our congress into a flat spin that it hasn't come out of except for the year following 9/11. Then came the Patriot Act which seemed more geared towards granting special powers than protecting Americans. Obama took the reigns and with that came the virus known as John Boehner which has infected the congress like some incurable zombie serum. And 2016 ain't looking too good either.

Somewhere around 1802..

But in all seriousness, they have never represented the American People, they have always represented they district or region or their constituents.

Virginia Senators don't care about California. California Senators don't care about Texas. So on and so forth. Additionally, the "traditional" policy when voting (before it became party lines) was Vote yes, if it didn't affect your state. Therefore, as long as it wasn't detrimental to your state, vote yes (it would live or die in the House based on it's merits).