  We report the discovery of a locus of stars in the SDSS g-r vs. u-g
color-color diagram that connects the colors of white dwarfs and M dwarfs.
While its contrast with respect to the main stellar locus is only ~1:2300, this
previously unrecognized feature includes 863 stars from the SDSS Data Release
1. The position and shape of the feature are in good agreement with predictions
of a simple binary star model that consists of a white dwarf and an M dwarf,
with the components' luminosity ratio controlling the position along this
binary system locus. SDSS DR1 spectra for 47 of these objects strongly support
this model. The absolute magnitude--color distribution inferred for the white
dwarf component is in good agreement with the models of Bergeron et al. (1995).
