It remains unclear whether opinions are shifting permanently on these matters, or whether support for immigration and trade is solidifying among Democrats and independents as part of a broader reaction against the policies of President Donald Trump.

Six in 10 Americans said immigration helps the nation more than it hurts—up 6 points since the last sounding, in September 2016. One-third of people in the survey said immigration hurts more than it helps.

The result, which marks the highest level of support for immigration dating to at least 2005, comes as Mr. Trump is asking lawmakers to fund a wall along the U.S. border with Mexico and has twice signed executive orders, blocked by federal courts, suspending entry from certain countries.