  We present the first comprehensive analysis of the argon K-edge absorption
region (3.1-4.2 \AA) using high-resolution HETGS {\it Chandra} spectra of 33
low-mas X-ray binaries. Utilizing R-matrix theory, we computed new K
photoabsorption cross-sections for {\rm Ar}~{\sc i}--{\rm Ar}~{\sc xvi}
species. For each X-ray source, we estimated column densities for the {\rm
Ar}~{\sc i}, {\rm Ar}~{\sc ii}, {\rm Ar}~{\sc iii}, {\rm Ar}~{\sc xvi}, {\rm
Ar}~{\sc xvii} and {\rm Ar}~{\sc xviii} ions, which trace the neutral, warm and
hot components of the gaseous Galactic interstellar medium. We examined their
distribution as a function of Galactic latitude, longitude, and distances to
the sources. However, no significant correlations were discerned among
distances, Galactic latitude, or longitude. Future X-ray observatories will
allow us to benchmark the atomic data as the main resonance lines will be
resolved.
