The M-1 Garand, the main rifle in WWII was and is 30-06....
Indeed.
To complete the picture ...
The .30-06 cartridge was designed for the M1903 Springfield rifle, US standard during WWI, as an improvement on the .30-03 cartridge. The M1917 Enfield rifle was also built to use the .30-06 cartridge and used extensively in WWI.
The M1 “Garand” was originally designed for a new .270 cal cartridge. Vast stocks of .30 M1 ammunition led to a requirement that the rifle be redesigned for that cartridge instead. And that’s why it has an 8 round clip, rather than 10.
You can still get 30-06 API ammo too.