The Bureau of Constabulary under the Idaho Department of Law Enforcement was established in May of 1919.

In March of 1929, the State Traffic Patrol was formed to address the matters of vehicular "high speed" on new asphalt roadways and the carnage that can sometimes come with it. By 1930, the fifteen man force collected auto license fees, set up light and brake testing stations, enforced spring highway load restrictions, suppressed gasoline bootleggers, kept irrigation water from eroding the highways and enforced all aircraft regulations as well! Their primary mandate however was to patrol the highways and reduce the collision rate.

By the end of 1930, over 2000 motorists on Idaho's highways were warned of traffic infractions and the most serious offenders found themselves in handcuffs. 21 Patrol Districts were set up and patrolled routinely. By 1938, US Route 95 known as the "North-South Highway" was completed and the need for stepped-up enforcement was required. In 1939, the Idaho State Police became the new name and organization that embodied the necessary authority to address all matters and manners of a state law enforcement mandate. In 1947, the Idaho State Police was up to 40 sworn officers and they received 40 new Chevrolet coupes with large diagonal stripes down both sides.

The birth of the "skunk car" as ISP marked patrol cars are known began. Strict enforcement of truck registration, weight and equipment laws by the Idaho State Police commenced with the "Port of Entry" program that went into full swing in 1952. This program alone required 25 officers to cover 44 counties to sustain it. The State Police became a separate division of the Department of Law Enforcement in 1955 and a superintendent appointed by the state governor became the man who administered and managed the agency. ISP marked patrol vehicles went to blue and white in 1965 and in 1978, they returned to the traditional black and white diagonal stripe. This was also the year that "bubble style" roof lights were replaced by light bars. In July of 1982, Port of Entry and Motor Vehicle Divisions were moved from the Department of Law Enforcement to the Idaho Transportation Department.

1983 saw delivery of twelve 5.0 liter Ford Mustangs for patrol. These 140 mph patrol cars required the specialized training of twelve lucky officers to manage the speed and handling of these hard-working vehicles. The ISP celebrated its 50th Anniversary on February 20 1989.

Idaho State Flag

A silk flag, blue field, five feet six inches fly,
and four feet four inches on pike, bordered with gilt
fringe two and one-half inches in width, with state seal of
Idaho twenty-one inches in diameter, in colors, in the center
of a blue field. The words "State of Idaho" are embroidered
in with block letters, two inches in height on a red
band three inches in width by twenty-nine inches in
length, the band being in gold and placed about eight and
one-half inches from the lower border of fringe and parallel with the same.

1929 issue Exempt plate.
Possible First-Issue Idaho State Police "State Traffic Patrol"
plate. If the pattern of issuance of "Ex"- Prefixed Exempt
plates in the 400 series bloc for ISP vehicles went back to
"day one", then this plate would have been issued to the 10th
vehicle of the newly formed 15-member traffic patrol.

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this type plate on duty....
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1939 Exempt Issue
Photo courtesy of Dan Coviello

Late 1940's issue
Large "EX" followed by a number in the 400's
Picture courtesy of Jack McGee

Picture courtesy of the Idaho State Police

1951 issue
EX followed by a number in the 400's
Picture courtesy of the Idaho State Police

1955 State Vehicle plate. Idaho State Police used
registrations in the 400 series.
Picture courtesy of Earl Jenson

1961 State Vehicle plate. Idaho State Police used an identical
3 digit plate at that time, however with a registration number
in the 400 series . The notation on the back of this plate
indicated that it was used by an Idaho State
Game Warden in Carey, Idaho.

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this type plate on duty....
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1975-1986 issue. 400-500 number bloc. 573 was car
and radio number. Early version with no dash separator,
darker background sheeting and non-seriffed letter "I" for
ISP. Same plate as one pictured on patrol vehicle to the right.
Picture courtesy of the Robert Ward Collection

1975-1986 issue. 400-500 number bloc. 586 was car
and radio number. Later version with dash separator,
brighter background sheeting and seriffed letter "I"
for ISP. Not certain what year the changeover between
this and preceding type took place.

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this type plate on duty....
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1986-1987 issue- This was a letter-coded government service exempt plate (# I 401 to # I 700), and it went over with ISP troopers like a lead balloon! By the Spring of 1987, these plates were replaced with the better-liked ISP prefixed plates.

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Summer 1987 issue- RARE type as these plates were put on hold due to introduction of Centennial base plates which came out roughly at the same time that year.

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1987-1991 issue- 400= Colonel/Director of Idaho State Police. Plate has vertical circular holograms down the center of the plate with the Idaho state shape and "87" inside.

1988-1991 issue- Plate has smaller dies and vertical circular holograms down the center of the plate with the Idaho state shape and "88" inside.

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this type plate on duty....
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1991-Current issue- Plate is same number as my 1975 issue.