1955 Louisiana Highway renumbering
In 1955, Louisiana passed a law that undertook a comprehensive revision to the state highway classification and numbering system.
The remainder of the numbering system seemed to work on a lower-number, higher-order principle, with some clustering; for instance, LA 61 and 62 both existed in St. Bernard Parish.
Other routes were added as time went on, numbered in consecutive fashion, starting with LA 99 in 1924.
Unlike today's system, clustering of the higher numbers seems to have occurred only when multiple routes in an area were added at the same time.
LA 33 was always discontinuous as ten miles of the New Orleans–Hammond Highway was never completed as planned through St. John the Baptist and St. Charles Parishes.
LA 1 did not match its legal description until 1928 when the Jefferson Highway was completed between Shrewsbury and New Orleans.
Post-war efforts to make improvements to Louisiana's unorganized highway-numbering system reached fruition at the 1955 legislative session, where a comprehensive highway bill was passed that year and enacted into law.
The new law effected a comprehensive revision of state highway classification and numbering, in order to designate roads by importance to travel patterns and to rectify the confusing numbering system by marking primary travel routes under unified designations.
One element of the highway reform lobby's efforts that was left out of the 1955 highway law was a proposal to reduce the amount of state-maintained mileage, mainly by shedding the many miles of minor and local service roads the state had accumulated over the years for political and other reasons.
No 2xx numbers were used; this range may have been intended as an expansion area for future primary route designations (this was never done).
State routes in any range can and have been removed from the system, and there are many corresponding gaps in the numerical sequence.
Despite the high numbers, some roadways in the 3XXX series are major, heavily trafficked thoroughfares; an example is LA 3132, a connector between I-20 and I-49 in Shreveport—and a rare example, in Louisiana, of a state highway built in the multilane, divided, access-fully-controlled format typical of interstate highways.
The Louisiana state highway system's most ubiquitous and unique anachronism is the infamous "hyphenated" routes.
For example, the LA 466 family originally had 17 sections, all within the city of Gretna in Jefferson Parish.
