We use observations from the array of North American GPS receivers to examine the formation and severity of midlatitude enhancements and steep gradients in total electron content (TEC) during the October 30--31, 2003 superstorm. A large (~10x) enhancement in dayside TEC was observed over the US mainland during these events as Dst decreased sharply and strong SAPS electric fields eroded the outer reaches of the post-noon plasmasphere boundary layer (PBL) forming poleward-streaming plumes of storm enhanced density. TEC increased to >250 TECu equatorward of the PBL. TEC gradients across the PBL over the central US exceeded 60 TECu per deg latitude. While intense, these features are qualitatively similar to those seen in lesser storms.