On March 29, the Pegasus oil pipeline, owned by ExxonMobil, ruptured in an upscale suburb of Little Rock, Ark. While the 5,000 to 7,000 barrel oil spill is dwarfed by the Deepwater Horizon spill from just a few years ago, it nonetheless raises serious questions about the safety of the large network of pipelines that crisscross the United States.