  We present a detailed study of the X-ray dust scattering halo of the black
hole candidate \cygx1 based on two \chandra\ HETGS observations. Using 18
different dust models, including one modified by us (dubbed XLNW), we probe the
interstellar medium between us and this source. A consistent description of the
cloud properties along the line of sight that describes at the same time the
halo radial profile, the halo lightcurves, and the column density from source
spectroscopy is best achieved with a small subset of these models. Combining
the studies of the halo radial profile and the halo lightcurves, we favor a
geometric distance to \cygx1 of $d=1.81\pm{0.09}$\,kpc. Our study also shows
that there is a dense cloud, which contributes $\sim$50% of the dust grains
along the line of sight to \cygx1, located at $\sim1.6$ kpc from us. The
remainder of the dust along the line of sight is close to the black hole
binary.
