Histograms showing CO velocity components above 5σ (light gray), CO emission groups/clouds (dark gray) and matched dust clumps (black outline) by galactocentric (upper) and heliocentric (lower) distance. The vertical dashed yellow line indicates the peak associated with local emission. The magenta and green shaded areas mark the distance range between 225° ≤ ℓ≤ 260° of theloci of the Perseus and Outer arms, respectively. The two peaks between r_gal ~ 12 and ~ 13 kpc correspond to complexes between the Perseus and Outer arm.