Trace of the Outer arm on the CfA CO survey integrated from ﹩b=-5^\circ \quad {\rm{to}}\quad +5^\circ ﹩. The survey was moment masked to suppress noise while integrating over such a large range of latitude. The traces of the Perseus and Outer Scutum–Centaurus arms are also shown for reference; note that the CO map here does not show those two arms optimally (see instead Figures 8 and 10). The emission near −70 km s⁻¹ between ﹩l=65^\circ \quad {\rm{and}}\quad 100^\circ ﹩ may be a bridge between the Perseus and Outer arms.