Many thanks to Michael Lindsay of Louisiana for providing this history and explanation of the variations of how mapmakers showed the Eastern Expressway in and near New Orleans.
The Eastern Expressway: the overpasses on I-10 are all dated 1964, 1965, or1966....they could be the construction you see on maps and the actual three lanes of concrete connecting them coming years later. In the case of I-10 in Metarie you have overpasses next to each other two years difference in dating, and being made of concrete but having the roadway made out of asphalt.
The Eastern Expressway
was there years before I-10 was proposed. It used to connect Downman Road
and Little Woods Highway which is now I-510. The entire Pontchartrain Expressway
was completed in 1959 and opened late in the year, it connected the Westbank
Expressway (still under construction at the time) and Ponchartrain
Blvd. Basically, I-10 connected pre-existing expressways and
right-of-ways at the time,which is why you have maps which show driveable
sections of the interstate there years before the interstate was
constructed.
As for the Lafitte-Larose
Highway, it made it to Laffite, but never to Larose. It is my understanding
that it's purpose was to shorten the trip to New Orleans from a highway
called ' The Dixie Expressway' which was to be
what is now the
I-49 corridor to new orleans from Lafayette. It was stopped because of
the impact building the highway would have on the marsh.