In my area, left turns not only were legal, but the person turning left had the "right of way" over any vehicles approaching from the opposite direction - at least up to around 1960 or so. That particular rule survived from the days long before "turn lanes" of any kind, and was to allow a driver who had to stop in the middle of the highway to turn to "get the f&@#$&! out of the way" as quickly as possible.

The rule doesn't appear in current regulations that I've found, and I don't find any indication of whether it was changed or just forgotten. Quite probably it was changed "officially"¹ when the rule-makers finally caught on to what most drivers then knew - that being right doesn't mean you'll live through attempting to assert your right.

¹ There was a massive general revision of statutes sometime around 1960, and I believe it was then that they amended the State Statute from a century earlier that said - verbatim: "If two trains meet on the same track both shall come to a complete stop and neither shall move until the other is gone."

John