Galactic ISM Constraints via Radio Point Sources

Gas and dust in the interstellar medium (ISM) comprises of order 10% of the mass of the Milky Way Galaxy. Here I will overview the history of using radio point sources, such as pulsars, OH/IR stars, and extragalactic sources, as line-of-sight probes of the local ISM. Combining these results provides constraints on the bulk properties of the ISM's structure. I will end with a summary of some current observations done and potential future steps in the analysis of this medium.