The invoking of national security to unravel trade agreements could scramble the international trading system in China’s favor.

Ties between the United States and Mexico have deepened over 30 years of free trade, creating both benefits and irritants.

Economists have long helped to shape policy on issues like taxes and health care. But flawed forecasts and arcane language have cost them credibility.

President-elect Donald J. Trump has moved beyond the team-of-rivals approach from his first term and chosen economic aides who will defend tariffs and tax cuts.

A multibillion-dollar expansion helped the canal accommodate king-size cargo ships. It might also be fueling ecological upheaval.