Don't see any same day turns avail, but there are next day. ORD-PDX $178 AI 5.1 CPM, route through SEA for $200 for 4.5 cpm with 500 mile min. Sample itinerary:
Chicago (ORD) to Portland (PDX) - Tue, Jan 15
Chicago (ORD) to Seattle (SEA) - Tue, Jan 15
Alaska Airlines 29 Dep: 3:30PM Arr: 6:00PM 4h 30m Boeing 737 Economy (T)
Layover in SEA 1h 0m
Seattle (SEA) to Portland (PDX) - Tue, Jan 15
Alaska Airlines 2047 Dep: 7:00PM Arr: 7:47PM 0h 47m De Havilland Dash-8 Economy (T)
OPERATED BY HORIZON AIR AS ALASKA AIRLINES
Portland (PDX) to Chicago (ORD) - Wed, Jan 16
Portland (PDX) to Seattle (SEA) - Wed, Jan 16
Alaska Airlines 2026 Dep: 11:00AM Arr: 11:50AM 0h 50m De Havilland Dash-8 Economy (T)
OPERATED BY HORIZON AIR AS ALASKA AIRLINES Layover in SEA 0h 55m
Seattle (SEA) to Chicago (ORD) - Wed, Jan 16
Alaska Airlines 22 Dep: 12:45PM Arr: 6:47PM 4h 2m Boeing 737 Economy (T)
Cost per passenger (including taxes & fees) $199.20
Total cost for 1 passenger $199.20
UA has the same price of $178 on Saturdays only until 1 March, but less useful -- 3 nights minimum, it seems. Non-stop ORD-PDX, so only 3478 EQM at $0.051/EQM. Too bad.