  We present a measurement of the Hubble Constant $H_0$ using the gravitational
wave event GW190412, an asymmetric binary black hole merger detected by
LIGO/Virgo, as a dark standard siren. This event does not have an
electromagnetic counterpart, so we use the statistical standard siren method
and marginalize over potential host galaxies from the Dark Energy Spectroscopic
Instrument (DESI) survey. GW190412 is well-localized to 12 deg$^2$ (90%
credible interval), so it is promising for a dark siren analysis. The dark
siren value for $H_0=85.4_{-33.9}^{+29.1}$ km/s/Mpc, with a posterior shape
that is consistent with redshift overdensities. When combined with the bright
standard siren measurement from GW170817 we recover $H_0=77.96_{-5.03}^{+23.0}$
km/s/Mpc, consistent with both early and late-time Universe measurements of
$H_0$. This work represents the first standard siren analysis performed with
DESI data, and includes the most complete spectroscopic sample used in a dark
siren analysis to date.
