Remember Spring ahead all through 70’s and 80’s as fourth Sunday of April (I see 74 and 75 were Jan and Feb). Then in 87 moved to first Sunday in April. Now second Sunday March well before Spring.
It changed to the current dates in 2007 and at that time I worked for a television station and you wouldn't believe how much grief it caused us with various automation and scheduling software packages that had the old spring and fall date rules baked into the software, and in some cases in the firmware.