What did the Wabash v. Illinois decision state regarding state regulation of railroads?

The decision in Wabash v. Illinois (1886) clarified the limits of state regulation over railroads, particularly concerning interstate commerce. The ruling determined that while states had the authority to regulate commerce that occurred within their own borders, they could not impose regulations on interstate trade. Therefore, states could control aspects of railroad operations that were purely intrastate, but any railroad activity that crossed state lines fell under the regulation of the federal government due to the Commerce Clause of the Constitution. This case significantly influenced the development of federal regulatory authority over transportation and commerce, leading to the eventual establishment of the Interstate Commerce Commission to manage these concerns. Thus, the answer regarding states being able to control trade but not interstate railroads accurately reflects the legal precedent established by this landmark decision.