Migrants from many countries are arriving at the US-Mexico border. Here's why

Encounters of migrants along the U.S.-Mexico border exceeded 2.3 million last year, an all-time high.

Two decades ago, when Border Patrol apprehensions also hit records, the vast majority of migrants who crossed the southern border illegally were adult males from Mexico seeking jobs in the U.S.

But the migrants arriving at the border today include not just men from Mexico, but also men, women and children, often entire families, from more than a dozen countries in the Western Hemisphere, notably Guatemala, Honduras, and El Salvador, and more recently, Cuba, Venezuela, Haiti, Nicaragua, Ecuador and Colombia.

Migrants also have been showing up at the southern border increasingly from countries on other continents, among them Russia, China, and India.