The magneto-ionic medium in the Milky Way
  One way in which the Canadian Galactic Plane Survey has made an important
contribution to the understanding of the Galactic interstellar medium is
through its polarization surveys. Investigation of these data has enabled a big
step in the study of magnetic fields in the interstellar medium and a range of
discrete, extended, interstellar objects. In this review, I will discuss the
role that the magnetic field plays in the interstellar medium, summarizing the
ways in which magnetic field interacts with the other components in the Milky
Way. Magnetic fields in the Galactic halo are discussed, and an outlook to a
number of successor surveys of the polarized CGPS in the near future is given.
