World economic freedom has reached record levels, according to the 2014 Index of Economic Freedom, released Tuesday by the Heritage Foundation and The Wall Street Journal. But after seven straight years of decline, the U.S. has dropped out of the top 10 most economically free countries.

For 20 years, the index has measured a nation's commitment to free enterprise on a scale of 0 to 100 by evaluating 10 categories, including fiscal soundness, government size and property rights. These commitments have powerful effects: Countries...