The typical keyboard layout of American typewriters made in the middle of the 20th century.
Notes:

While the arrangement of Latin letters of the letter block was universal throughout all typewriters (except in some European countries like French AZERTY or German and East European QWERTZ), the arrangement of punctuation marks, additional and special symbols might vary. This is the layout that was standardized by around the 1930s and 1940s.
The button 1 ! may be absent from many portable models (thus 1 was typed as the lowercase l, and an exclamation mark was typed as an apostrophe plus a dot).
The two extreme right buttons (in gray colour) might be potentially present on some models though they were extremely rare. Most typewriters lack these buttons.
In early models (pre-1940s) button , might have ? in the upper register, e.g. , ?, while / ? was changed to / ¾.
x over it: 272 International keyboard layouts
The Typewriter Database
Typewriter Manuals / Richard Polt's The Classic Typewriter Page
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