What this tells us is 1 million "NA" serial numbered sewing machines were manufactured in 1951, 1 million "NB" serial numbered sewing machine were manufactured in 1956 and 1 million "NB" serial numbered sewing machine were manufactured in 1961.
Anderson, South Carolina Singer had one United States manufacturing factory, Elizabethport, located in Elizabeth, New Jersey.
Dating your singer sewing machine
I also used specific events, assorted reference materials, original owner purchase receipts and instruction manual revised dates.
Here is the "Year of Issue" Serial Number Database Summary!
All sewing machines manufactured their never had a suffix after the model number.
After 1900 all models manufactured overseas now included a suffix after the model number to denote the place of manufacture.
After the last Singer Model 503A sewing machine was manufactured in 1963 the Anderson plant stayed open for many years with 3 manufacturing lines: Sewing Machines, Floor-care products (vacuum cleaners) and Power Tools.