Although nearly all companies enjoy some degree of protection over the use of their logos, not all companies go through the steps to obtain trademarks. The degree and geographical scope of the protection depends on the type of trademark for which a company has filed.
Simply by using it in a public setting, a company earns a limited trademark over its logo. This limited trademark only protects the logo in the immediate geographical area surrounding the company's base of operations. By filing with the Secretary of State, a company can trademark its logo throughout a state. Companies can also file for trademarks with the federal government, which protects the logo throughout the entire nation.