Why are people more pro-trade than pro-migration?

About this book

"I analyze individual attitudes towards trade and immigration in comparative terms. I find that individuals are on average more pro-trade than pro-immigration across several countries. I identify a key source of this difference: the cleavage in trade preferences, absent in immigration attitudes, between individuals working in traded as opposed to non-traded sectors"--Forschungsinstitut zur Zukunft der Arbeit web site.