The latest measurements of the cross sections for
singly-produced top quarks at the Fermilab Tevatron are presented.
The small expected signals and the large, uncertain backgrounds require
careful event selection, sophisticated methods for separating signal
events from background events, and data-based background predictions
and fits.  Both the CDF and D0 collaborations have solid evidence of
single top production, using 2.7 fb-1 and 0.9 fb-1 of data, respectively.
Both collaborations perform several analyses to measure the total
single-top cross section sigma_s + sigma_t, as well as sigma_s and
sigma_t separately.