[gruez]

>This isn't marketing fraud because you aren't being sold transisters like you buy lumber at Home Depot.

Funny you say that, because "two by fours" used to be 2" x 4”, but became progressively thinner as manufacturing processes improved.

[nimajneb]

I thought it was because they planed the wood for you, a 2x4 is 2x4 before kiln drying and planing. https://www.thesprucecrafts.com/why-isnt-a-2x4-a-2x4-3970461

That said I'm not sure why they don't sell it by it's actual size.

[gruez]

>However, even the dimensions for finished lumber of a given nominal size have changed over time. In 1910, a typical finished 1-inch (25 mm) board was 13⁄16 in (21 mm). In 1928, that was reduced by 4%, and yet again by 4% in 1956. In 1961, at a meeting in Scottsdale, Arizona, the Committee on Grade Simplification and Standardization agreed to what is now the current U.S. standard: in part, the dressed size of a 1-inch (nominal) board was fixed at 3⁄4 inch; while the dressed size of 2 inch (nominal) lumber was reduced from 1 5⁄8 inch to the current 1 1⁄2 inch.[11]

https://en.wikipedia.org/wiki/Lumber#Dimensional_lumber

[lttlrck]

Despite the change from unfinished rough cut to more dimensionally stable, dried and finished lumber, the sizes are at least standardized by NIST. Still a funny observation!