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|Miles in Idaho
border near Post Falls, Idaho
border east of Mullan
interstates; U.S. 95 meets I-90 in Coeur d'Alene
Falls, Coeur d'Alene, Kellog, Wallace
count in 2005
|48,877, Post Falls
6,392, Mullan traffic recorder
Interstate 90 journey
Route 4, now
known as a portion of Interstate 90, begins in northern Idaho at the Idaho/Washington
state line and runs east through Coeur d’Alene and Wallace before leaving
the state at the Montana state line. At about 84 miles, this original part of
the Mullan Road was intended to connect the mighty Columbia River on the West
Coast with the Missouri River ( the western-most navigable waterway that connects
to the Mississippi River and beyond).
route travels through Post Falls, Coeur d’Alene, then through the mining
country towns of Wallace, Kellogg (originally, the town was named “Jackass,”
according to Cort Conley’s Idaho for the Curious) and Mullan, before entering
has the distinction of having the last traffic signal along a planned interstate
highway. Years of controversy delayed construction of Interstate 90 through
But on Sept. 12, 1991, the $40 million viaduct bypass opened, clearing the way
for non-stop east/west traffic. Two days later, the town held a celebration
to bury the stoplight. City Councilman Mike Aldredge told a crowd of more than
1,000 people that “Cruel progress has eliminated the need for the services
of our old friend.” (Public Roads, January/February 2006).
To avoid complications
from having the interstate pass through the heart of Wallace as originally planned,
residents added the city to the National Register of Historic Places in 1976.
As a result, I-90 was routed away from town through a narrow mountain corridor
by constructing a viaduct. U.S. 10 became Business Loop I-90, and the business
loop was the defacto route for the interstate through the mid- to late 1980s
while the bypass was constructed.
I-90 bypass opened to traffic in 1991, and the traffic signal was retired a
short time thereafter. That traffic signal later was returned to service on
a Wallace intersection and remains functioning today.
I-90 is the
longest east-west interstate in the nation, beginning in Seattle, Wash., and
ending in Boston, Mass., a distance of 3,020.54 miles.
For a historic
perspective I-90 between Seattle and Missoula, Montana, please download a pdf
file "The Evolution of Interstate 90 Between Seattle and Missoula,"
by Erick Johnson, Eastern Washington Untiversity, first published in 1995 and
revised in 2006.