The Solar Neighborhood XXXV: Distances to 1404 M Dwarf Systems Within 25 pc in the Southern Sky

We present trigonometric, photometric, and photographic distances to 1748 southern ($\delta \leq$0$^\circ$) M dwarf systems with $\mu \ge$ 0\farcs18 yr$^{-1}$, of which 1404 are believed to lie within 25 parsecs of the Sun. The stars have 6.67 $\leq$ $V_J$ $\leq$ 21.38 and 3.50 $\leq$ ($V_J-K_s$) $\leq$ 9.27, covering the entire M dwarf spectral sequence from M0.0V through M9.5V. This sample therefore provides a comprehensive snapshot of our current knowledge of the southern sky for the nearest M dwarfs that dominate the stellar population of the Galaxy. Roughly one-third of the 1748 systems, each of which has an M dwarf primary, have published high quality parallaxes, including 179 from the RECONS astrometry program. For the remaining systems, we offer photometric distance estimates that have well-calibrated errors. The bulk of these ($\sim$700) are based on new $V_JR_{KC}I_{KC}$ photometry acquired at the CTIO/SMARTS 0.9m telescope, while the remaining 500 primaries have photographic plate distance estimates calculated using SuperCOSMOS $B_JR_{59F}I_{IVN}$ photometry. Confirmed and candidate subdwarfs in the sample have been identified, and a census of companions is included.