  We investigate the relationship between the spatial distributions of stellar
populations and of neutral and ionized gas in the Local Group dwarf irregular
galaxy Sextans A. This galaxy is currently experiencing a burst of localized
star formation, the trigger of which is unknown. We have resolved various
populations of stars via deep UBV(RI)_C imaging over an area with diameter \sim
5.'3. We have compared our photometry with theoretical isochrones appropriate
for Sextans A, in order to determine the ages of these populations. We have
mapped out the history of star formation, most accurately for times \lesssim
100 Myr. We find that star formation in Sextans A is correlated both in time
and space, especially for the most recent (\lesssim 12 Myr) times. The youngest
stars in the galaxy are forming primarily along the inner edge of the large H I
shell. Somewhat older populations, \lesssim 50 Myr, are found inward of the
youngest stars. Progressively older star formation, from \sim 50--100 Myr,
appears to have some spatially coherent structure and is more centrally
concentrated. The oldest stars we can accurately sample appear to have
approximately a uniform spatial distribution, which extends beyond a surface
brightness of \mu_B \simeq 25.9 mag arcsec^{-2} (or, a radius r \simeq 2.'3$).
Although other processes are also possible, our data provides support for a
mechanism of supernova-driven expansion of the neutral gas, resulting in cold
gas pileup and compression along the H I shell and sequential star formation in
recent times.
