  We redetermine the relationship between absolute magnitude and orbital period
for dwarf novae, based on 46 stars with good distance estimates. This improves
upon Warner's previous relation, building upon today's improved estimates of
distance and binary inclination, and greater wavelength coverage. Together with
other distance and dynamical constraints, this calibration is then applied to a
set of ~300 known or likely dwarf novae of short orbital period, to study the
dependence of quiescent M_v, time-averaged M_v, mass ratio q, and white-dwarf
temperature T_WD, on P_orb. These distributions show that stars become much
fainter as they approach minimum P_orb, and appear to show /evolutionary
tracks/ as the secondary is whittled down by mass loss. Stars on the lower
branch have the expected properties of "period bouncers" -- with a feeble
secondary, faint accretion light, cool white dwarf, and long recurrence time
between eruptions. Period bounce seems to occur at a mass of 0.058+-0.008
M_sol. Stars on the lower branch may also have higher velocities and heights
above the Galactic plane, consistent with a greater age. Some are very nearby,
despite strong selection effects discriminating against the discovery of these
faint binaries accreting at very low rates. Period bouncers appear to be very
common, and probably would dominate a complete census of cataclysmic variables.
