What is a Collectible Typewriter?

Most modern conventional typewriters until 1960 worked on the "front strike" principle. This refers to the printing mechanism. The printing letters are mounted on the ends of rods called "type bars." Front-striking type bars rest horizontally and swing forward to strike the roller at the front.
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With that in mind, here is a rule of thumb to distinguish conventional from unconventional typewriters.

A conventional typewriter has:
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four rows of keys ---- single-shift
ribbon inking -----front-strike type bars
Underwood, 1895 -- Cool, but just conventional.

The 4-row, front-strike format was established by Underwood in 1895. It was used on almost all manual and electric typewriters until IBM changed the industry with its "golf ball" Selectric in 1960. Collectors generally prefer unconventional typewriters for their collections, though early or fine examples of some conventional machines may also be collectible. Most collectible typewriters date from 1874 to about 1915. Only those 100 or more years old are genuine "antiques."