345:
373:
786:
26:
73:
359:
745:
258:
243:
137:
106:
101:
96:
659:
91:
593:
by following Warm
Springs Avenue along the north side of the Boise River. The state government approved a realignment that truncated the highway at the Gowen Road interchange on I-84 in 1980. A temporary routing was used while a new four-lane highway between the freeway and SH-21 near Lucky Peak Dam
410:
on a bridge constructed in 1996, and connects with Warm
Springs Avenue, old SH-21, from east Boise. The highway heads upstream, briefly as a four-lane divided highway, along the north bank of the river in a
450:
at 6,117 feet (1,864 m), and with Beaver Creek to the Beaver Creek Summit at 6,041 feet (1,841 m) ten miles (16 km) further. Following this summit, SH-21 descends 2,240 feet (683 m) in
426:
Above the Lucky Peak Dam, SH-21 climbs over the
Highland Valley Summit (3,782 ft (1,153 m)), then descends to just above the reservoir. It then crosses the Mores Creek
1266:
1261:
1256:
1226:
482:
ravaged the area around Lowman in 1989; it destroyed 45,000 acres (70 sq mi; 180 km) and 26 structures, but without injuries or fatalities.
602:. The new bridge over the Boise River began construction in March 1995 and was opened the following year. The former alignment was transferred to the
821:
1235:
857:
216:
400:
563:
and continues due north for a mile, then veers east with the twisty main Salmon River as it descends to
Clayton, then north towards
517:
317:
1251:
948:
930:
828:
799:
226:
51:
221:
528:. About four miles (6.5 km) west of Stanley is the turnoff for the three-mile (5 km) spur road to the photogenic
1099:
603:
416:
1072:
391:. The highway is an eastern extension of Gowen Road, which runs along the southern and western perimeter of the
509:
466:
At Lowman is the intersection with the
Wildlife Canyon Scenic Byway, which descends with the South Fork of the
396:
1126:
446:. After Idaho City, the highway continues to climb with Mores Creek for another 13 miles (21 km) to the
1039:
505:
832:
752:
748:
674:
670:
666:
662:
540:
486:
475:
406:
After three miles (5 km) eastbound from I-84, Highway 21 descends and crosses the New York Canal and
384:
310:
261:
246:
140:
121:
117:
113:
109:
1152:
765:
Northern terminus; SH-75 north is the Salmon River Scenic Byway, SH-75 south is the
Sawtooth Scenic Byway
485:
North of Lowman, SH-21 ascends the South Fork of the
Payette River to Grandjean, on the west side of the
908:
443:
861:
516:. At "Cape Horn" the highway turns southeast to gradually climb with Marsh Creek to the border of the
994:
727:
713:
686:
599:
521:
513:
501:
191:
1044:
696:
490:
333:
298:
187:
328:
and its tributary Mores Creek to the Boise Basin and beyond, and then the upper South Fork of the
969:
447:
1217:
791:
760:
682:
641:
595:
431:
302:
183:
344:
556:
321:
1178:
1057:
732:
590:
564:
552:
525:
439:
420:
377:
348:
294:
144:
1245:
756:
701:
568:
548:
467:
456:
392:
329:
306:
163:
717:
678:
646:
529:
508:, and descends northward with Banner Creek and Cape Horn Creek, tributaries of the
452:
372:
366:
352:
290:
125:
533:
407:
362:
325:
539:
In
Stanley, SH-21 terminates at 6,250 feet (1,905 m) at the junction with
1016:
781:
316:
The road is designated as one of Idaho's scenic byways and provides access to
1073:"Dollar detour: 'Desert' route linking Idaho 21, I-84 may be built in stages"
583:
494:
460:
435:
427:
594:
was planned in the 1980s. The realigned SH-21 would also serve an expanded
358:
574:
The upper elevations of SH-21 are often closed during the winter months.
479:
1179:"Regular Meeting of the Idaho Transportation Board, January 21–22, 1997"
430:
and ascends with it to the Boise Basin gold mining area centered around
471:
412:
883:
25:
1225:
691:
Southern terminus; I-84 exit 57; road continues west as Gowen Road
371:
357:
343:
286:
173:
297:, primarily as a two-lane road. With two-thirds of its length in
388:
559:. North of the intersection in Stanley, Highway 75 becomes the
1184:. Idaho Transportation Department. January 22, 1997. p. 2
586:
connecting Boise with the gold mining areas near Idaho City.
770:
1.000 mi = 1.609 km; 1.000 km = 0.621 mi
598:
facility and residential development on land owned by the
1213:
1208:
582:
Portions of the highway originated in the 1860s, as a
387:
southeast of Boise, exactly 3,000 feet (910 m)
937:. Associated Press. September 22, 1989. p. B1.
712:Wildlife Canyon Scenic Byway (Banks-Lowman Road) –
532:at 6,513 feet (1,985 m), framed by the jagged
403:) to connect with Orchard Road at exit 52 of I-84.
201:
179:
169:
159:
154:
131:
85:
80:
65:
57:
44:
21:
493:at 7,056 feet (2,151 m), the route's maximum
313:, then along their northern boundary to Stanley.
816:
814:
489:, and climbs the Canyon Creek tributary to the
955:. Associated Press. July 30, 1990. p. A9.
520:, where SH-21 enters the drainage of the main
949:"'Against all the odds,' Lowman forest heals"
497:, over 3,200 feet (980 m) above Lowman.
8:
1227:Template:Attached KML/Idaho State Highway 21
931:"Lowman blaze cleanup to cost $ 3.6 million"
1019:. Historical Marker Database. (Idaho - 266)
989:
987:
1100:"Hearing set on Gowen four-lane connector"
903:
901:
613:
235:
1230:
964:
962:
567:, where the route terminates and rejoins
500:At the Banner Creek Summit, SH-21 enters
415:canyon. The route passes the century-old
886:. (Ada County, Idaho): BridgeReports.com
470:through a canyon popular for whitewater
810:
1267:Transportation in Custer County, Idaho
722:Elevation 3,800 ft (1,160 m)
61:130.869 mi (210.613 km)
18:
1262:Transportation in Boise County, Idaho
742:
736:
711:
705:
656:
650:
16:State highway in Idaho, United States
7:
1127:"Micron's risk is beautiful to J.R."
419:(1909), and several miles later the
1257:Transportation in Ada County, Idaho
1038:Anderson, Steven (April 11, 1980).
459:at 3,801 feet (1,159 m) above
1125:Bailey, Julie (October 20, 1994).
1071:Funaiole, Linda (March 18, 1981).
628:
14:
1040:"Proposal to alter Idaho 21 OK'd"
518:Sawtooth National Recreation Area
318:Sawtooth National Recreation Area
822:"State Highway 21 Milepoint Log"
784:
743:
657:
256:
241:
135:
104:
99:
94:
89:
71:
24:
829:Idaho Transportation Department
800:List of state highways in Idaho
589:SH-21 originally terminated in
571:just south of the city limits.
332:and a tributary from Lowman to
909:"Wildlife Canyon Scenic Byway"
831:. May 15, 2015. Archived from
536:at 9,860 feet (3,005 m).
376:Northern terminus of SH-21 at
1:
1238:- Ponderosa Pine Scenic Byway
1153:"Water delays work on bridge"
1098:Abe, Debby (April 16, 1984).
860:. Visit Idaho. Archived from
858:"Ponderosa Pine Scenic Byway"
623:
555:to the south, originating in
1151:Eckart, Kim (May 17, 1995).
1167:– via Newspapers.com.
1140:– via Newspapers.com.
1114:– via Newspapers.com.
1087:– via Newspapers.com.
995:"Salmon River Scenic Byway"
604:Ada County Highway District
383:SH-21 begins at exit 57 of
324:. It primarily follows the
309:to the western edge of the
283:Ponderosa Pine Scenic Byway
76:Ponderosa Pine Scenic Byway
1283:
561:Salmon River Scenic Byway,
210:Idaho State Highway System
769:
764:
739:
731:
726:
721:
708:
700:
695:
690:
653:
645:
640:
635:
632:
627:
622:
619:
616:
524:, and gently descends to
417:Boise River Diversion Dam
234:
206:
197:
150:
49:
37:
884:"SH-21 over Boise River"
301:, it passes by historic
285:, is a state highway in
39:SH-21 highlighted in red
1252:State highways in Idaho
970:"Sawtooth Scenic Byway"
506:Challis National Forest
474:, westward to Banks at
380:
369:
355:
606:on February 1, 1997.
545:Sawtooth Scenic Byway
444:Boise National Forest
423:, completed in 1955.
375:
361:
347:
281:), also known as the
1231:KML is from Wikidata
953:The Spokesman-Review
935:The Spokesman-Review
864:on September 6, 2015
600:J.R. Simplot Company
1157:The Idaho Statesman
1130:The Idaho Statesman
1104:The Idaho Statesman
1077:The Idaho Statesman
1045:The Idaho Statesman
1017:"The Old Toll Road"
610:Major intersections
491:Banner Creek Summit
334:Banner Creek Summit
320:from Boise and the
305:and the village of
455:to the village of
448:Mores Creek Summit
397:Air National Guard
381:
370:
356:
311:Sawtooth Mountains
792:U.S. Roads portal
775:
774:
596:Micron Technology
340:Route description
272:
271:
268:
267:
45:Route information
1274:
1221:
1194:
1193:
1191:
1189:
1183:
1175:
1169:
1168:
1166:
1164:
1148:
1142:
1141:
1139:
1137:
1122:
1116:
1115:
1113:
1111:
1095:
1089:
1088:
1086:
1084:
1068:
1062:
1061:
1055:
1053:
1035:
1029:
1028:
1026:
1024:
1013:
1007:
1006:
1004:
1002:
991:
982:
981:
979:
977:
966:
957:
956:
945:
939:
938:
927:
921:
920:
918:
916:
905:
896:
895:
893:
891:
880:
874:
873:
871:
869:
854:
848:
847:
845:
843:
838:on March 5, 2016
837:
826:
818:
794:
789:
788:
787:
747:
746:
661:
660:
630:
625:
614:
478:. A devastating
275:State Highway 21
264:
260:
259:
249:
245:
244:
236:
139:
138:
108:
107:
103:
102:
98:
97:
93:
92:
75:
74:
31:State Highway 21
28:
19:
1282:
1281:
1277:
1276:
1275:
1273:
1272:
1271:
1242:
1241:
1232:
1229:
1224:
1223:
1222:
1206:
1202:
1197:
1187:
1185:
1181:
1177:
1176:
1172:
1162:
1160:
1150:
1149:
1145:
1135:
1133:
1124:
1123:
1119:
1109:
1107:
1097:
1096:
1092:
1082:
1080:
1070:
1069:
1065:
1051:
1049:
1037:
1036:
1032:
1022:
1020:
1015:
1014:
1010:
1000:
998:
993:
992:
985:
975:
973:
968:
967:
960:
947:
946:
942:
929:
928:
924:
914:
912:
907:
906:
899:
889:
887:
882:
881:
877:
867:
865:
856:
855:
851:
841:
839:
835:
824:
820:
819:
812:
808:
790:
785:
783:
780:
771:
744:
658:
612:
580:
389:above sea level
342:
322:Treasure Valley
289:. It runs from
257:
255:
242:
240:
136:
105:
100:
95:
90:
81:Major junctions
72:
67:
40:
33:
32:
29:
17:
12:
11:
5:
1280:
1278:
1270:
1269:
1264:
1259:
1254:
1244:
1243:
1240:
1239:
1205:
1204:
1203:
1201:
1200:External links
1198:
1196:
1195:
1170:
1143:
1117:
1090:
1063:
1058:Newspapers.com
1030:
1008:
983:
958:
940:
922:
897:
875:
849:
809:
807:
804:
803:
802:
796:
795:
779:
776:
773:
772:
767:
766:
763:
741:
738:
735:
730:
724:
723:
720:
710:
707:
704:
699:
693:
692:
689:
655:
652:
649:
644:
638:
637:
634:
631:
626:
621:
618:
611:
608:
591:Downtown Boise
579:
576:
442:forest of the
440:Ponderosa pine
434:, leaving the
421:Lucky Peak Dam
349:Lucky Peak Dam
341:
338:
270:
269:
266:
265:
252:
250:
232:
231:
230:
229:
224:
219:
213:
212:
204:
203:
202:Highway system
199:
198:
195:
194:
181:
177:
176:
171:
167:
166:
161:
157:
156:
152:
151:
148:
147:
133:
132:North end
129:
128:
87:
86:South end
83:
82:
78:
77:
69:
63:
62:
59:
55:
54:
50:Maintained by
47:
46:
42:
41:
38:
35:
34:
30:
23:
22:
15:
13:
10:
9:
6:
4:
3:
2:
1279:
1268:
1265:
1263:
1260:
1258:
1255:
1253:
1250:
1249:
1247:
1237:
1234:
1233:
1228:
1219:
1215:
1211:
1210:
1199:
1180:
1174:
1171:
1158:
1154:
1147:
1144:
1131:
1128:
1121:
1118:
1105:
1101:
1094:
1091:
1078:
1074:
1067:
1064:
1059:
1047:
1046:
1041:
1034:
1031:
1018:
1012:
1009:
997:. Visit Idaho
996:
990:
988:
984:
972:. Visit Idaho
971:
965:
963:
959:
954:
950:
944:
941:
936:
932:
926:
923:
911:. Visit Idaho
910:
904:
902:
898:
885:
879:
876:
863:
859:
853:
850:
834:
830:
823:
817:
815:
811:
805:
801:
798:
797:
793:
782:
777:
768:
762:
758:
754:
753:Lower Stanley
750:
734:
729:
725:
719:
715:
714:Garden Valley
703:
698:
694:
688:
687:Mountain Home
684:
680:
676:
672:
668:
664:
648:
643:
639:
615:
609:
607:
605:
601:
597:
592:
587:
585:
577:
575:
572:
570:
566:
562:
558:
554:
550:
549:Galena Summit
546:
542:
537:
535:
531:
527:
523:
519:
515:
511:
507:
503:
502:Custer County
498:
496:
492:
488:
483:
481:
477:
473:
469:
468:Payette River
464:
462:
458:
454:
449:
445:
441:
438:to enter the
437:
433:
429:
424:
422:
418:
414:
409:
404:
402:
398:
394:
393:Boise Airport
390:
386:
385:Interstate 84
379:
374:
368:
364:
360:
354:
350:
346:
339:
337:
335:
331:
330:Payette River
327:
323:
319:
314:
312:
308:
304:
300:
296:
292:
288:
284:
280:
276:
263:
253:
251:
248:
238:
237:
233:
228:
225:
223:
220:
218:
215:
214:
211:
208:
207:
205:
200:
196:
193:
189:
185:
182:
178:
175:
172:
168:
165:
164:United States
162:
158:
153:
149:
146:
142:
134:
130:
127:
123:
119:
115:
111:
88:
84:
79:
70:
64:
60:
56:
53:
48:
43:
36:
27:
20:
1207:
1188:February 11,
1186:. Retrieved
1173:
1163:February 11,
1161:. Retrieved
1159:. p. 1B
1156:
1146:
1136:February 11,
1134:. Retrieved
1132:. p. 1A
1129:
1120:
1110:February 11,
1108:. Retrieved
1106:. p. 1C
1103:
1093:
1083:February 11,
1081:. Retrieved
1079:. p. 1C
1076:
1066:
1056:– via
1052:February 11,
1050:. Retrieved
1048:. p. 2B
1043:
1033:
1021:. Retrieved
1011:
999:. Retrieved
974:. Retrieved
952:
943:
934:
925:
913:. Retrieved
888:. Retrieved
878:
866:. Retrieved
862:the original
852:
840:. Retrieved
833:the original
633:Destinations
588:
581:
573:
560:
544:
538:
530:Stanley Lake
522:Salmon River
514:Salmon River
499:
484:
465:
425:
405:
382:
367:Stanley Lake
315:
299:Boise County
282:
278:
274:
273:
209:
1236:Visit Idaho
1023:October 24,
1001:October 24,
976:October 24,
915:October 24,
868:October 24,
842:October 24,
534:McGown Peak
510:Middle Fork
453:switchbacks
408:Boise River
401:Gowen Field
363:McGown Peak
326:Boise River
1246:Categories
806:References
761:Sun Valley
683:Twin Falls
675:US 30
671:US 26
667:US 20
476:Highway 55
432:Idaho City
303:Idaho City
217:Interstate
122:US 30
118:US 26
114:US 20
677:) –
584:toll road
495:elevation
487:Sawtooths
461:sea level
436:sagebrush
428:tributary
395:(and the
1209:KML file
890:March 8,
778:See also
751: –
673: /
669: /
620:Location
557:Shoshone
504:and the
480:wildfire
180:Counties
155:Location
120: /
116: /
112: /
733:Stanley
578:History
565:Challis
553:Ketchum
526:Stanley
512:of the
472:rafting
378:Stanley
295:Stanley
160:Country
145:Stanley
66:Tourist
757:Salmon
740:210.61
737:130.87
728:Custer
709:116.85
702:Lowman
617:County
543:, the
457:Lowman
413:basalt
365:&
307:Lowman
192:Custer
68:routes
58:Length
1182:(PDF)
836:(PDF)
825:(PDF)
749:SH-75
718:Banks
706:72.61
697:Boise
679:Boise
647:Boise
636:Notes
569:US-93
547:from
541:SH-75
353:Boise
351:near
291:Boise
287:Idaho
279:SH-21
262:SH-22
247:SH-19
227:State
188:Boise
174:Idaho
170:State
141:SH-75
126:Boise
1218:help
1214:edit
1190:2023
1165:2023
1138:2023
1112:2023
1085:2023
1054:2023
1025:2011
1003:2015
978:2015
917:2015
892:2020
870:2015
844:2015
663:I-84
654:0.00
651:0.00
551:and
110:I-84
642:Ada
399:'s
293:to
184:Ada
143:in
124:in
52:ITD
1248::
1216:•
1155:.
1102:.
1075:.
1042:.
986:^
961:^
951:.
933:.
900:^
827:.
813:^
759:,
755:,
716:,
685:,
681:,
629:km
624:mi
463:.
336:.
254:→
239:←
222:US
190:,
186:,
1220:)
1212:(
1192:.
1060:.
1027:.
1005:.
980:.
919:.
894:.
872:.
846:.
665:(
277:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
