Poland is now among the world's 20 largest economies. How did it happen? It's a historic leap from the post-communist ruins of 1989-90 to today’s European growth champion.

A generation ago, Poland rationed sugar and flour while its citizens were paid one-tenth what West Germans earned. Today its economy has edged past Switzerland to become the world’s 20th largest with over $1 trillion in annual output. It's a historic leap from the post-communist ruins of 1989-90 to today’s European growth champion that economists say has lessons on how to bring prosperity to ordinary people — and that the Trump administration says should be recognized by Poland’s presence at a summit of the Group of 20 leading economies later this year In 35 years — a little less than...