  Using data from the 2MASS All-Sky Point Source Catalogue, we have extended
our census of nearby ultracool dwarfs to cover the full celestial sphere above
Galactic latitute 15 degrees. Starting with an initial catalogue of 2,139,484
sources, we have winnowed the sample to 467 candidate late-type M or L dwarfs
within 20 parsecs of the Sun. Fifty-four of those sources already have
spectroscopic observations confirming them as late-type dwarfs. We present
optical spectroscopy of 376 of the remaining 413 sources, and identify 44 as
ultracool dwarfs with spectroscopic distances less than 20 parsecs. Twenty-five
of the 37 sources that lack optical data have near-infrared spectroscopy.
Combining the present sample with our previous results and data from the
literature, we catalogue 94 L dwarf systems within 20 parsecs. We discuss the
distribution of activity, as measured by H-alpha emission, in this
volume-limited sample. We have coupled the present ultracool catalogue with
data for stars in the northern 8-parsec sample and recent (incomplete)
statistics for T dwarfs to provide a snapshot of the current 20-parsec census
as a function of spectral type.
