  We have imaged the halo populations of a sample of nearby spiral galaxies
using the Wide Field Planetary Camera 2 on broad the Hubble Space Telescope
with the aim of studying the stellar population properties and relating them to
those of the host galaxies. In four galaxies, the red-giant branch is
sufficiently well populated to measure the magnitude of the tip of the
red-giant branch (TRGB), a well-known distance indicator. Using both the Sobel
edge-detection technique and maximum-likelihood analysis to measure the
$I$-band magnitude of the red giant branch tip, we determine distances to four
nearby galaxies: NGC 253, NGC 4244, and NGC 4945, NGC 4258. For the first three
galaxies, the TRGB distance determined here is more direct, and likely to be
more accurate, than previous distance estimates. In the case of NGC 4258, our
TRGB distance is in good agreement with the the geometrical maser distance,
supporting the the Large Magellanic Cloud distance modulus $(m-M)_0 = 18.50$
that is generally adopted in recent estimates of the Hubble constant.
