Oregon

I would come straight west from Cody on 14 through Yellowstone, take Hwy US 20 to Twin Falls across I 15 to I84. Then US 20 near Ontario, OR to Eugene, then south to Grant Pass.
Option would be to turn south at Bend, then south to OR 140 near Lakeview

Time Mile Instruction For Toward
Summary: 1205.8 miles (2 days, 1 hour, 25 minutes)
DAY 1
Check your departure time; the next stop is in a different time zone.
9:00 AM 0.0 Depart Cody on US-14 (US-16) (East) 76 yds
9:00 AM 0.1 Turn LEFT (North) onto US-14A (WY-120) 0.4 mi
9:01 AM 0.5 Turn LEFT (West) onto WY-120 (Belfry Hwy) 37.4 mi
9:33 AM 37.9 Entering Montana
9:33 AM 37.9 Road name changes to MT-72 (Highway 72) 10.6 mi
9:42 AM 48.4 Turn RIGHT (East) onto MT-72 (Vaill Ave) 10.9 mi
9:52 AM 59.3 Turn LEFT (North) onto US-310 (US Highway 310) 17.9 mi
10:08 AM 77.2 Turn RIGHT (East) onto US-212 [US-310] 11.6 mi
10:19 AM 88.8 Turn RIGHT (East) onto Ramp 87 yds I-90 W / Butte
10:19 AM 88.9 Take Ramp (RIGHT) onto I-90 206.7 mi
1:13 PM 295.6 Road name changes to I-15 [I-90] 7.6 mi
1:20 PM 303.2 At exit 121, road name changes to I-90 258.9 mi I-90 W / Missoula
4:23 PM 520.6 Entering Idaho
Check local time; this stop is in a different time zone.
5:00 PM 562.2 End of day
DAY 2
9:00 AM 562.2 Stay on I-90 49.3 mi
9:27 AM 594.2 Entering Washington
9:42 AM 611.4 At exit 282B, turn RIGHT onto Ramp 0.1 mi Second Avenue
9:43 AM 611.5 Keep STRAIGHT onto E 2nd Ave 0.1 mi
9:43 AM 611.7 Turn LEFT (South) onto S Perry St 153 yds
9:44 AM 611.7 Road name changes to E Liberty Park Pl 142 yds
9:44 AM 611.8 Turn RIGHT (South) onto Local road(s) 43 yds
9:45 AM 611.9 At I-90, return North on Local road(s) 43 yds
9:45 AM 611.9 Turn LEFT (West) onto E Liberty Park Pl 142 yds
9:45 AM 612.0 Road name changes to S Perry St 153 yds
9:46 AM 612.0 Bear LEFT (West) onto E 2nd Ave, then immediately bear RIGHT (North-West) onto Ramp 0.7 mi
9:48 AM 612.7 Turn LEFT to stay on Ramp 0.3 mi I-90 / Second Ave
9:48 AM 613.0 Take Ramp (LEFT) onto I-90 61.0 mi I-90 W / Seattle
10:41 AM 674.0 At exit 220, turn RIGHT onto Ramp 0.6 mi US-395 S / Ritzville / Pasco
10:41 AM 674.5 Take Ramp (LEFT) onto US-395 73.1 mi US-395 S / Pasco
11:43 AM 747.6 Take Ramp (RIGHT) onto I-182 (US-12) 2.4 mi I-182 W / US-395 S / Pendleton / Richland
11:46 AM 750.0 At exit 12A, turn LEFT onto Ramp 0.7 mi US-395 S / Pendleton / Kennewick
11:47 AM 750.7 Road name changes to US-395 7.0 mi
11:55 AM 757.7 Take Ramp (LEFT) onto I-82 [US-395] 18.9 mi I-82 E / US-395 S / Pendleton / Umatilla
12:11 PM 776.6 At exit 131, turn RIGHT onto Ramp 0.3 mi WA-14 W / Plymouth / Vancouver
12:11 PM 777.0 Turn RIGHT (West) onto WA-14 62.3 mi
1:05 PM 839.2 Bear RIGHT (North-West) onto WA-14 [Highway 14] 15.7 mi
1:19 PM 854.9 Bear RIGHT (West) onto WA-14 1.2 mi
1:20 PM 856.1 Turn LEFT (South) onto US-97 2.4 mi
1:23 PM 858.2 Entering Oregon
1:23 PM 858.5 Turn RIGHT (South-West) onto Local road(s) 142 yds I-84 W / US-30 W / The Dalles
1:23 PM 858.6 Take Ramp onto I-84 [US-30] 101.8 mi I-84 W / US-30 W
2:52 PM 960.3 Turn LEFT onto Ramp 0.3 mi I-5 S / Salem / Beaverton / City Center
2:52 PM 960.7 Take Ramp (LEFT) onto I-5 (Pacific Hwy) 146.2 mi I-5 S / Beaverton / Salem
5:00 PM 1106.8 End of day
DAY 3
9:00 AM 1106.8 Stay on I-5 [OR-99] 97.3 mi
10:22 AM 1204.2 At exit 58, turn RIGHT onto Ramp 0.3 mi OR-99 / US-199 / Redwood Hwy / City Center / Grants Pass
10:22 AM 1204.5 Keep STRAIGHT onto US-199 (OR-99) 1.3 mi
10:25 AM 1205.8 Arrive Grants Pass

SUMMARY
Driving distance: 1205.8 miles
Trip duration: 2 days, 1 hour, 25 minutes
Driving time: 17 hours, 25 minutes
Cost: $133.99

old guy wrote:
if it were me I would get on I 90 and get into Washington state, at Ritzville turn south on I 82 to I 84 head west on I 84 then south on I 5 to grants Pass. freeway all the way.

That's about the route we're planning on to get to Portland. But we have a stop in Ritzville to see an old friend and want to see SD and MT sites we missed years ago on our previous cross country trips.

You will get info on *this* forum, but it might help to try

posting your question (new wording - no dupes allowed) in the

*Roads and Routes* forum (It's under "Locations" in the forums list).

.

if it were me I would get on I 90 and get into Washington state, at Ritzville turn south on I 82 to I 84 head west on I 84 then south on I 5 to grants Pass. freeway all the way.