Distribution of 2857 dynamically young Cepheids in the Galactic plane. The dark blue points show the positions of the dynamically young Cepheids. The positions of the Galactic centre (+) and the Sun (⊙) are indicated, and the overlaid polar grid shows the galactic longitude in 30° intervals and heliocentric distances at 3 kpc intervals. The shaded region shows the shadow cone caused by high extinction in the Cygnus X star formation region. The Galactic quadrants are indicated with Roman numerals.