A History of Short Words

From the New York Times Crossword Puzzle

SSR

Sun, 15 Aug '21
Ukr. or Lith., formerly
Sun, 11 Jul '21
Tajikistan, e.g., once: Abbr.
Tue, 23 Feb '21
Map abbr. until 1991
Sun, 31 Jan '21
Union member of the 20th century, for short
Sun, 10 Jan '21
Kirghizia or Byelorussia: Abbr.