This article analyses the role that US states play in enforcing federal natural gas pipeline regulations. The paper finds that states are more likely to have responsibility for enforcing these regulations if they have larger networks of gathering and transmission lines and if their citizens are more liberal and more pro-environment. Conversely, states with a larger natural gas industry are less likely to assume oversight. However, whether a state has assumed oversight has no significant effect on either state enforcement efforts or pipeline performance. The most effective state enforcement tool is monetary penalties, which significantly decrease incidents and property damage.