Underwood 4-Bank Standard Portable
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The Underwood 4-Bank Standard Portable was the first portable typewriter produced by Underwood.
As a result of the 1920 Remington Portable No. 1 -- the first portable typewriter with 4 rows of keys-- making the existing Underwood 3-Bank Standard Portable somewhat obsolete, Underwood decided to develop a portable typewriter with 4 rows of keys.  Underwood designer Kurowski was told to develop a portable typewriter similar to the 3-Bank portable design. The Underwood Portable began production in 1926 and was highly successful, with over 1.25 million produced. 
Notes and Misc./Reference List
- ↑ 1.0 1.1 Underwood 4-Bank Portable, Perard et Al. Retrieved February 2, 2023.