During and after the 2016 election campaign, many observers said that there was widespread discontent with the way things were going. For example, a Reuters story in late September said "Polls show an electorate hungry for change, with a majority believing the country is on the wrong track." Donald Trump himself mentioned those polls: "Seventy-five percent of the American people, based on all polls, think our country is headed on the wrong track." He was exaggerating a bit, but it was a definite majority--about 60-65%.
The question, "do you feel that things in this country are generally going in the right direction today, or do you feel that things have pretty seriously gotten off on the wrong track?" was first asked in 1971, and repeated a number of times in the 1970s and early 1980s. Sometime in the middle of the 1980s, a lot of survey organizations adopted it, and since then it's been asked very frequently, probably over a thousand times. (There have been some variations in question wording, but they don't seem to make much difference.) I don't have time to transcribe that much data, so starting in 1982, I just considered the last poll before each Presidential or midterm election, plus polls from early September and late October 2001 in order to see the effect of the 9/11 attacks (which was a substantial increase in "right direction" answers). The figure shows the difference between percent choosing "right direction" and percent choosing "wrong track" (usually between 5-10% aren't sure).
By historical standards, opinions in 2016 were not unusual. In the last survey taken before the election, 31% chose "right direction" and 62% chose "wrong track," for a score of -31. That was nowhere near the low of October 2008 (14% to 79% for -65). There were obvious reasons for alarm then, but in October 1990, 19% chose "right direction" and 79% chose "wrong track." It would be interesting to try to figure out what causes change in answers to the "right direction/wrong track" question, but at this point I just want to observe that in 2016 the American public was not especially discontented about how things were going in the country.
Since Trump is so different from previous presidents, it's natural to think that his election must result from some profound discontent in the public. But for a lot of voters, as I've said in a number of previous posts, I think it was just another election between a Republican and a Democrat (and a Democrat who was strongly identified with the party, making it hard for her to pick up Republican votes). The basic circumstances were favorable to the Republicans--the economy was OK but not great, and the Democrats had been in office for two terms. Trump got only 45.95% of the vote, less than what Mitt Romney got in 2012 and only 0.3% more than what John McCain got in 2008, suggesting that he cost the party a significant number of votes.
The fact that Trump got the Republican nomination may indicate that there was profound discontent among Republicans, at least those who vote in the primaries. But Americans in general weren't especially discontented--it's normal for a majority to say that things are on the wrong track.
[Data from the Roper Center for Public Opinion Research]