2x4’s were never 2” by 4”
2” x 4”s were, but they were not kiln dried and surfaced.
I salvaged wood from an 1860s house that had actual 2xs and cut nails. Only time I have seen actually 2xs.
“2x4’s were never 2” by 4”
Yes they were. The house I owned in Nashville was 2x4 Oak, built in 1908.
Yes they were, but not in the 1960s. I helped renovate an ancient house in Atlanta that was built around 1880. The 2X4s were made of solid oak and were not planed smooth. We could pull nails out of those, had to saw the off or break them. We couldn't pound nails in either unless we pre-drilled. The electrical wiring was bare copper, phases run separately using porcelain "knob and tubing".
Today's 2X4s are originally sawed to exactly 2X4, then generously planed smooth.
If you renovate older houses you will run into “actual” 2 x 4’s occasionally. I renovated a small (20’x 20’) house that was studded completely with actual 2x4 studs, It was built around 1920. The studs were rough cut and and surprisingly appeared to be oak. They were very dark brown and real pain to drill through to run new wiring.
I have seen the real 2x4s in many houses and buildings that I have helped wreck since the 60s and even my beach shack in San Diego had them, and have reused them doing projects for my dad, and I saw them in the old barns in the upper Midwest.
Currently I have a friend who gives me junk lumber he pulls from an old abandoned restaurant/motel and the boards from the older portions are the original measurements.