Pipeline affecting most of the east coast.

[Anomalocaris]

A remnant of Cold War geopolitical concern.   It would be much more economic to put the refineries in Alaska, refine the crude there, and ship the intermediate and final product to the lower 48 rather to ship the crude to the lower 48 for refining.
But Alaska was too close to Russia.  Growth an vital refining industry in Alaska was thought to make the US more susceptible to Soviet blackmail.

That's a small part of it.

The big parts were WWII then NIMBY.

They did not want the Japanese to be able to capture refineries - so they didn' t build them.

Post WWII the locals just did not want the mess of refineries there.

The bulk of oil Alaska’s oil reserve wasn’t discovered until 1968.