SFO/BOS/IAD/NYC to LIS from $160 o/w (all 3 alliances, BE)
SFO/BOS/IAD/NYC to LIS is discounted by all three alliances. Either o/w starting from ~$160 or r/t for $350 or so. These book into basic economy. Wide availability, search via GF, book direct.
A few examples:
SFO-EWR-LIS: $164; UA; 12/13/21
SFO-JFK-LIS: $164; DL; 06/18/21
SFO-MAD-LIS; $174; IB; 07/26/21
EWR-LIS; $160; UA; 08/16/21
BOS-YYZ-LIS; $164; AC; 11/4/21