Colleges and universities in the United States attract more than a million international students a year. Higher education is one of America’s top service exports, generating $42 billion in revenue. But the money spigot is closing. The pandemic, visa restrictions, rising tuition and a perception of poor safety in America have driven new international student enrollment down by a jaw-dropping 72 percent. Read more: The U.S. may never regain its dominance as a destination for international students. Here's why that matters.