1939 Development completed on the 51st anniversary of the Parker Pen Company.
1939-40 Parker “51” test-marketed in South America and Caribbean countries.
1940 Parker “51” test-marketed in selected U.S. cities.
1941 The Parker “51” is introduced in the U.S. market.
1941 Parker “51” Ink introduced
1946 Parker “51” Red Band filler introduced and made for approx. 1 year
1947 Parker “51” vac demi introduced and made for 2 years
1947 Plain arrow clip introduced
1947 Blue Diamond clip discontinued mid-year
1948 Last year for vacumatic “51”
1948 Last year for vacumatic demi Parker “51”
1948 Aerometric Filler Parker “51” in demi and full sizes
1948 Parker “51” Signet in all gold filled cap and barrel
1948 Superchrome Ink introduced
1949 Parker “51” Presidential in all 14kt cap, barrel and clip
1949 Parker “51” Flighter in all stainless cap and barrel with gold cap band
1950 Parker “51 Special introduced
1951 Arrow clip shortened
1952 Last year for barrel dating on pens
1954 Parker “51” Jotter ballpoint introduced
1955 Liquid Lead pencil introduced
1956 Last year for pencil dating
1957 Rotary pencil introduced for regular “51s”
1957 Last year for Superchrome on filler sleeve
1958 “Signet” model renamed the “Insignia”
1958 “Bandless” Flighter introduced and made through 1960
1958 Parker “halo” logo added to cap
1960 Breather hole moved to the side of barrel
1961 Demi model discontinued
1961 Converter version introduced; made only approx. 2 years
1962 Finger clutch introduced
1964 Cap “lip” removed
1965 “51” imprint on cap
1965 new one-piece filler sleeve without black plastic end cap
1969 MKII introduced; “61” look-alike with pearl jewel cap, greater barrel taper, flat end
1971 MKIII introduced; same as MKII but with chrome jewel
* Years are as close as possible, but it must be noted that most changes often took place over a period of months. It is also very common to find pens that have been fixed over the years and have parts exchanged with earlier or later models