Some people, of course, reached farther back into history. The year the Declaration of Independence was signed, 1776, got a few votes. One person chose 1789, the year the Constitution took effect. One person chose 1800. One chose 1860, the year Southern states began to secede from the Union. But most answers were of a more recent vintage.

There were partisan patterns in views of America’s greatness. Republicans, over all, recall the late 1950s and the mid-1980s most fondly. Sample explanations: “Reagan.” “Economy was booming.” “No wars!” “Life was simpler.” “Strong family values.” The distribution of Trump supporters’ greatest years is somewhat similar to the Republican trend, but more widely dispersed over the last 70 years. Supporters of Ted Cruz picked best years that were similar to the party’s trend over all. The sample of John Kasich supporters in the survey was too small to detect any patterns.

As a group, Democrats seem to think America’s greatest days were more recent; they were more likely to pick a year in the 1990s, or since 2000. After 2000, their second-most-popular answer was 2016. Sample explanations: “We’re getting better.” “Improving social justice.” “Technology.” Even 2008, a year of financial collapse, was pretty popular, perhaps because President Obama was also elected that year. The pattern for supporters of Bernie Sanders was a little different from that of Hillary Clinton supporters: The main difference is that Mr. Sanders’s voters were more likely to pick a year from the 1960s, and more of the Clinton supporters chose best years in the 1990s, when her husband was president.

The Morning Consult survey was conducted with help of Lucid, a survey technology firm, over two days last week. The survey, conducted online, consisted of 2,003 interviews with registered voters.