Shares of U.S. Steel (NYSE: X) have been red-hot over the past year, surging nearly 60%. Driving those gains has been a significant improvement in the company's earnings due to higher steel prices. In the first quarter, the steelmaker reported $57 million, or $0.32 per share, of adjusted earnings, which was a vast improvement from the adjusted loss of $145 million, or $0.83 per share, it reported in the year-ago quarter.