We present observations and modeling of Low Frequency (LF; 30-300 kHz) and Medium Frequency (MF; 300-3000 kHz) signals during 21-August-2017 “Great American Solar Eclipse” using Nationwide Differential GPS (NDGPS) transmitters as a signal of opportunity. Apparent forward and back scattering from the eclipse totality spot is presented for the first time. The effect of the solar eclipse on the D-region electron density is investigated using FDTD modeling. The waveguide parameters of the totality spot are estimated to be h’ = 80 +/- 3 km and β = 0.9 +/- 0.1 km. The transition from an obscured ionosphere to a fully eclipsed ionosphere may be slow, 10s of seconds, but the transition from a fully eclipsed ionosphere to obscured likely occurred quite fast, less then a second, when the Sun’s influence reappeared.