The cause of HI velocity dispersions in the interstellar medium (ISM) of galaxies is often attributed to star formation, but recent evidence has shown these two quantities are not connected in regions of low star formation. This lack of connection is most apparent in dwarf galaxies and the outer disks of spiral galaxies. ...

In this thesis, I present a comparison between recent Sloan Digital Sky Survey (SDSS) Galactic studies and N-body simulations to aid in the interpretation of observed structural features. I investigate the origin of the Galactic thin/thick disk system and the contents of the Galactic halo by drawing comparisons to two high ...