  We present medium resolution spectroscopy and multi-epoch VRI photometry for
21 new nearby (< 50 pc) white dwarf systems brighter than V ~ 17. Of the new
systems, ten are DA (including a wide double degenerate system with two DA
components), eight are DC, two are DZ, and one is DB. In addition, we include
multi-epoch VRI photometry for eleven known white dwarf systems that do not
have trigonometric parallax determinations. Using model atmospheres relevant
for various types of white dwarfs (depending on spectral signatures), we
perform spectral energy distribution modeling by combining the optical
photometry with the near-infrared JHK from the Two Micron All-Sky Survey to
derive physical parameters (i.e., effective temperature and distance
estimates). We find that twelve new and six known white dwarf systems are
estimated to be within the NStars and Catalog of Nearby Stars horizons of 25
pc. Coupled with identical analyses of the 56 white dwarf systems presented in
Paper XIX of this series, a total of 20 new white dwarf systems and 18 known
white dwarf systems are estimated to be within 25 pc. These 38 systems of the
88 total studied represent a potential 34% increase in the 25 pc white dwarf
population (currently known to consist of 110 systems with trigonometric
parallaxes of varying qualities). We continue an ongoing effort via CTIOPI to
measure trigonometric parallaxes for the systems estimated to be within 25 pc
to confirm proximity and further fill the incompleteness gap in the local white
dwarf population. Another 38 systems (both new and known) are estimated to be
between 25 and 50 pc and are viable candidates for ground-based parallax
efforts wishing to broaden the horizon of interest.
