In 1919 Connecticut installed machinery in the state prison at Somers to begin production of markers for 1920 registrations.  Almost all passenger markers used in the state since that time have been manufactured at Somers or the Cheshire Correctional Facility.  The new markers were of painted steel featuring embossed numbers, letters and raised borders for greater rigidity.  The number of passenger registrations in Connecticut had continued to climb, exceeding 100,000 for the first time in 1921.  Consistent with previous practice the width of the marker varied with the number of digits.  The six digit markers were almost 18 inches wide and often difficult to mount on the vehicles of the day.

Production of the markers was a relatively simple process.  Raw material consisted of coils of sheet steel supplied to the state in the required width.  A slitter first cut the blanks to the required length. The blanks next went to presses that stamped the embossed numbers, state name abbreviation, year and stiffening borders into them.  The markers were then fed into a combination spray booth and drying oven.  A thin coating of quick drying background color enamel paint was sprayed on the backs, dried, and then the fronts received a thicker layer of the same material.  The contrasting color paint was then applied to the raised portions of the marker with a roller system.   After drying, the marker pairs were inspected and placed manually in mailing envelopes printed with the appropriate marker numbers.  In 1923 the use of raised painted borders for passenger markers was discontinued and replaced with de-bossed edges.  Painted raised borders would not be used again until late-1946.

 In 1924, after the DMV had established a number of branch offices in various cities around the state, markers began to be issued with a single letter prefix assigned to specific geographic areas.  As markers were assumed to have a one-year life the state used a relatively low quality paint that was thinly applied.  The red base paint used for the 1927, 1929, and 1931 years was particularly susceptible to bubbling and cracking on hot, sunny days.  The 1928 markers were a very dark charcoal with a hint of blue and rapidly discolored even after a short period of use.