At 0000 UTC 10 June (00Z/10), the leading upper-level STJ disturbance crossed the Rockies and helped organize diurnally forced convection over the higher terrain into a Mesoscale Convective System (MCS) over western New Mexico and eastern Texas. As the MCS moved southeast toward the Gulf of Mexico, mid-level vorticity associated with the MCS moved northeast toward Oklahoma. This mid-level vorticity triggered a second MCS over central Oklahoma by 00Z/11,which developed into a mature MCV by 18Z/11 over southern Missouri and northern Arkansas. This MCV could be tracked northeast to northern New York and southern Canada by 00Z/14. Noteworthy aspects of this MCV were: 1) its longevity, 2) its growth as a mid-level disturbance toward the surface, 3) its upshear tilt in lowest 6 km as evident from profiler observations, 4) its ability to reorganize convection, and 5) its interaction with an existing baroclinic zone over the Great Lakes. The purpose of this talk is to present the structural evolution of this long-lived MCV from its incipient phase to its transition into a frontal cyclone. Loops and figures are available at http://www.atmos.albany.edu/student/tomjr/meso05.html.