My understanding is a trademark usually involves a brand name, like the commercial name of a product a company makes. It's not the same as the name of the company, which is registered with the government (like with a state's Secretary of State's office) and is use in legal documents, tax returns, etc. I don't believe that expires.
Trains magazine's recent story on the "new" Rock Island in Mississippi noted the railroad had to get permission of the company that owns the rights to the Rock Island name before proceeding, even though there hasn't been a Rock Island RR for 40 years.
