The structures of the magnetic fields in the ‘spurs’ of non-thermal galactic radio emission are investigated by making use of the observed polarization and brightness distribution of the radio emission and data on the optical interstellar polarization. In at least two cases the magnetic fields are remarkably well aligned over large areas, and in four cases the field is parallel to the ridge of the corresponding spur. Comparison of the magnetic field direction with the planes of optical interstellar polarization yields an estimated distance of 100 ± 20 pc for the principal ridge of the North Galactic Spur. These facts severely restrict possible theories of these objects.