  Two Compact Steep-spectrum Sources (CSSs), 0548+165 and 1524-136, chosen from
a list of CSSs with polarization percentages that decrease with decreasing
frequency and high rotation measure values (RM > 450 rad/m**2) on arcsecond
scales, were observed with the VLBA at 4.9 and 8.4 GHz. RM values up to ~10**4
rad/m**2 were found in several regions along the jets in both sources. We
suggest that a thin screen of magneto-ionic material with about 1 kpc thickness
is responsible for these high RMs. The observed depolarization may be due to
beam depolarization and/or inhomogeneities in the magnetic field.
