Highway 78

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Idaho State Highway 78

Generally following the Snake River, Idaho Highway 78 travels 99.65 miles southeast from SH 55 at Marsing to I-84/U.S. 26-30 at Hammett. SH 78 replaced Business Loop I-84 north 1.08 miles from Old Highway 30 in Hammett to Interstate 84 at Exit 112. The business loop was decommissioned after 2016. It continued east from SH 78 (Main Street) along Old Highway 30 to the half diamond interchange (Exit 114) joining I-84 with Cold Springs Road.

Idaho State Highway 78 East
SH 78 parallels the Snake River east from Indian Cove before turning north into Elmore County.
SH 78 parallels the Snake River east from Indian Cove before turning north into Elmore County.
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The Snake River separates Owyee and Elmore Counties west to the Ada County line and east to Schoffs Island.
The Snake River separates Owyee and Elmore Counties west to the Ada County line and east to Schoffs Island.
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SH 78 curves north from Spangler Road onto Main Street into unincorporated Hammett.
SH 78 curves north from Spangler Road onto Main Street into unincorporated Hammett.
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SH 78 (Main Street) dog legs west along Old U.S. 30 at the Hammett business district. Old U.S. 30 was formerly Business Loop I-84 east to I-84 at Exit 114.
SH 78 (Main Street) dog legs west along Old U.S. 30 at the Hammett business district. Old U.S. 30 was formerly Business Loop I-84 east to I-84 at Exit 114.
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Eastbound SH 78 previously ended at Business Loop I-84 (Old U.S. 30).
Eastbound SH 78 previously ended at Business Loop I-84 (Old U.S. 30).
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The old Hammett Railroad Bridge along Old U.S. 30 crossing the Union Pacific Railroad east of Hammett was eventually replaced.
The old Hammett Railroad Bridge along Old U.S. 30 crossing the Union Pacific Railroad east of Hammett was eventually replaced.
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Traffic to I-84 is directed to remain on SH 78 eastbound to I-84 at Exit 112. Previously trailblazers referenced eastbound to use Business Loop I-84 to Exit 114.
Traffic to I-84 is directed to remain on SH 78 eastbound to I-84 at Exit 112. Previously trailblazers referenced eastbound to use Business Loop I-84 to Exit 114.
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SH 78 commences south from a diamond interchange (Exit 112) joining I-84/U.S. 26-30 with Hammett Hill Road.
SH 78 commences south from a diamond interchange (Exit 112) joining I-84/U.S. 26-30 with Hammett Hill Road.
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The first confirming marker for Business Loop I-84 east into Hammett appeared south of I-84/U.S. 26-30 ahead of Whitworth Drive. It was eventually replaced with a shield for SH 78.
The first confirming marker for Business Loop I-84 east into Hammett appeared south of I-84/U.S. 26-30 ahead of Whitworth Drive. It was eventually replaced with a shield for SH 78.
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SH 78 spans a Union Pacific Railroad line south of Waller Drive.
SH 78 spans a Union Pacific Railroad line south of Waller Drive.
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Business Loop I-84 turned east onto Old U.S. 30 one block ahead of where SH 78 ended.
Business Loop I-84 turned east onto Old U.S. 30 one block ahead of where SH 78 ended.
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SH 78 continues south from Old U.S. 30 (former Business Loop I-84) in Hammett along Main Street.
SH 78 continues south from Old U.S. 30 (former Business Loop I-84) in Hammett along Main Street.
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Idaho State Highway 78 West
The distance to Elko, Nevada references SH 78 west to SH 51 south, which becomes Nevada State Route 225.
The distance to Elko, Nevada references SH 78 west to SH 51 south, which becomes Nevada State Route 225.
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SR 78 curves west from Main Street in Hammett at Riverview Road.
SR 78 curves west from Main Street in Hammett at Riverview Road.
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SH 78 straddles the north side of the Snake River before turning south across the waterway.
SH 78 straddles the north side of the Snake River before turning south across the waterway.
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SH 78 west enters Owyhee County across the Snake River.
SH 78 west enters Owyhee County across the Snake River.
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Page Updated Tuesday April 07, 2026.