The news that Microsoft has offered $44.6 billion for Yahoo underscores yet again, in this campaign season, the remarkable contributions of immigrants to the American economy. Yahoo’s chief executive officer and co-founder, Jerry Yang, was born Yang Zhiyuan in Taiwan and, in 1978, immigrated to California at age 10. At the top ranks of American technology entrepreneurship, he joins Google co-founder Sergey Brin, who emigrated from Russia in 1979 at age 6, and Intel’s former chairman and chief executive officer, Andrew Grove, who came to America from Hungary in the 1950s. Without Google, without Yahoo, and without Intel, the main industry in Silicon Valley would still be avocado farming, and America’s economy, and the world’s, would be the poorer for it. The oldest of these four companies — Yahoo, Google, Microsoft, and Intel — is Intel, founded in 1968, just 40 years ago. It’s a tribute to the dynamism and innovation that make America and American-style capitalism great — and something to remember the next time some politician, pundit, or activist describes immigration as a problem rather than a source of American vitality and strength.