Positions at present (circles) and 15 Myr ago (end of the lines having their origin at the present position of each star) for the 23 red supergiants in Cygnus having measured proper motions and radial velocity. The sample is divided as in Fig. 6, with the younger and older samples separated in two panels for clarity. The galactic longitude and latitude are defined as they would be measured by an observer moving with the circular velocity along the solar circle and located at the present time at the position of the Sun.