The railroad operator's 21,000 miles of track touch 23 states (plus D.C. and Canada) and more than 70 ports in the U.S. Though its revenues and profits were flat -- $11.8 billion and $1.9 billion, respectively -- CSX (No. 231) boasts a safety record for 2012: the lowest rate of personal injury in the company's history. The railroad titan is in the midst of building the National Gateway, a public-private project that will improve links between Mid-Atlantic ports and the Midwest for freight trains. The company will spend $575 million on the improvements, which are slated for completion in 2015.
Wal-Mart retook the top spot, Berkshire Hathaway made the top five, and Apple grew enormously.