The General Social Survey has documented a great decline in support for the proposition that you can generally trust people. In 1984, equal numbers agreed and disagreed with that statement. In 2010, there was a thirty percentage point gap, with those who felt that you couldn't trust people outnumbering those who felt that you could by about 62% to 32%. It is a long term trend, with minor bumps along the way, whose causes aren't manifestly obvious.
Indeed, it is counter to what you would expect in some respects. For example, having more education is strongly tied to having more trust in others. But, the decline in trust has taken place despite modestly rising education levels in that time period.