United Airlines and American Airlines have low $68 to $88 one way fares between San Francisco and Chicago for travel from February to May 2016. Both airlines offer a few dates with $68 fares over the next month and both American and United have several dates in April and May 2016 with $88 one-way fares. Round trip tickets can be purchased for $136.20 to $176.20.
United Airlines Chicago ORD – San Francisco SFO (nonstop)
$136.20 Monday Feb 22 – Wednesday March 2
American Airlines has a couple of dates, March 8 and 9, with $69 fares for SFO-ORD, but there are no $69 fares from ORD to SFO. Search one way fares to find a low fare round trip combination, or consider flying AA one way and United one way to combine low one way fares.
There are low fare same day returns available with American Airlines for mileage run purposes.
American Airlines Chicago ORD – San Francisco SFO
$176.20 Tuesday April 12 – Tuesday April 19
American Airlines Chicago ORD – San Francisco SFO – Chicago ORD = 3,692 flight miles.