There were a number of varieties produced during this eleven year span.  The principal types produced subsequent to the original 1937 design were:

1. Production of military aircraft during World War Two required huge quantities of aluminum.  In early 1942 the federal government took control of all of that metal the country could produce for the war effort.  During the war years of 1942-1945, Connecticut, after the existing stock of aluminum plate sheeting was exhausted, switched to making marker plates of steel for new passenger registrations.  These markers were painted black over a light gray background with the backs also gray.  They carried prefix numbers two through seven over a letter on the left and one to three numbers to the right.  There were no new automobiles produced during the war and this situation coupled with severe gasoline rationing resulted in limiting the number of new registrations.   

2.  In 1946 with the war ended, the state returned to producing the 1937-1941 style markers in aluminum.  They continued forward with the prefix number-over-letter system used during the war.  The top number of the prefix on this variant is almost always a seven or eight unless it was a replacement marker. 

3.  In late-1946 and into the first part of 1947 markers in Connecticut were made from rose colored brass sheeting that was excess war production.  They were painted black with a dull silver background and had a raised black border.  The backs were normally left unpainted.  These markers always have a nine over a letter prefix.  The particular brass employed was quite soft, deformed easily and did not make a very suitable base material for markers.  In addition these markers suffered from poor bonding of the paint to the brass.  The paint would soon flake off even in moderate use and occasionally peel off large areas of the flat surface within a short time of installation. 

4.  To remedy this problem the state put into production during 1947 a series of markers made of very thin gauge aluminum.  They were painted black over silver with a raised black border.  For new registrations this variant has a letter over a number prefix.  These markers were very fragile due to their thinness and few have survived the passage of time in good condition.