  (Abridged) We analyze blazar jet apparent speeds and accelerations from the
RDV series of astrometric and geodetic VLBI experiments. From these
experiments, we have produced and analyzed 2753 global VLBI images of 68
sources at 8 GHz with a median beam size of 0.9 milliarcseconds (mas), and a
median of 43 epochs per source. From this sample, we analyze the motions of 225
jet components in 66 sources. The distribution of the fastest measured apparent
speed in each source has a median of 8.3c and a maximum of 44c. Sources in the
2FGL Fermi LAT catalog display higher apparent speeds than those that have not
been detected. On average, components farther from the core in a given source
have significantly higher apparent speeds than components closer to the core.
We measure accelerations of components in orthogonal directions parallel and
perpendicular to their average velocity vector. Parallel accelerations have
significantly larger magnitudes than perpendicular accelerations, implying
observed accelerations are predominantly due to changes in the Lorentz factor
(bulk or pattern) rather than projection effects from jet bending. Positive
parallel accelerations are significantly more common than negative ones, so the
Lorentz factor (bulk or pattern)tends to increase on the scales observed here.
Observed parallel accelerations correspond to modest source frame increases in
the bulk or pattern Lorentz factor.
