  We present a measurement of the Hubble constant $H_0$ from surface brightness
fluctuation (SBF) distances for 63 bright, mainly early-type galaxies out to
100 Mpc observed with the Wide Field Camera 3 Infrared Channel (WFC3/IR) on the
Hubble Space Telescope (HST). The sample is drawn from several independent HST
imaging programs using the F110W bandpass of WFC3/IR. The majority of galaxies
are in the 50 to 80 Mpc range and come from the MASSIVE galaxy survey. The
median statistical uncertainty on individual distance measurements is 4%. We
construct the Hubble diagram with these IR SBF distances and constrain $H_0$
using {four} different treatments of the galaxy velocities. For the SBF zero
point calibration, we use both the existing tie to Cepheid variables, updated
for consistency with the latest determination of the distance to the Large
Magellanic Cloud from detached eclipsing binaries, and a new tie to the tip of
the red giant branch (TRGB) calibrated from the maser distance to NGC4258.
These two SBF calibrations are consistent with each other and with theoretical
predictions from stellar population models. From a weighted average of the
Cepheid and TRGB calibrations, we derive $H_0=73.3{\,\pm\,}0.7{\,\pm\,}2.4$
km/s/Mpc, where the error bars reflect the statistical and systematic
uncertainties. This result accords well with recent measurements of $H_0$ from
Type~Ia supernovae, time delays in multiply lensed quasars, and water masers.
The systematic uncertainty could be reduced to below 2% by calibrating the SBF
method with precision TRGB distances for a statistical sample of massive
early-type galaxies out to the Virgo cluster measured with the James Webb Space
Telescope.
