Almost all Singer Featherweights, both models 221 and 222K, have a serial number that begins with an "A" or an "E".
Singer Featherweight machines that were made in the USA have prefixes that begin with "A". They were produced in the Singer factory in Elizabethport, NJ. The first Singer 221 Featherweights were produced in the USA in 1933 and had serial numbers that began with "AD". The last Featherweight 221 machines produced in the USA were made in 1957 and had serial numbers that began with "AM".
Canadian Singer Featherweight machines have a more complex serial number story than the USA produced Featherweights. This is because 221, 221K and 222K machines were assembled in Canada.
Singer Featherweight machines from Canada had their "hulls" produced in the UK at the Singer factory in Kilbowie, Scotland. The hulls were then shipped to the Singer factory in St Johns, Quebec to be assembled for the Canadian and American markets. Consequently, the prefixes for Canadian Featherweights begin with "E" which is the same prefix as UK machines. However there were a few Canadian assembled 221 Featherweights that had serial numbers that began with "J". The very few that did not begin with "E" are discussed toward the end of the blog.
Canadian Singer 221 Featherweights started being assembled in Canada in 1949 with serial numbers beginning with "EE" and stopped being assembled in 1961. The 1961 machines had serial numbers that began with "ES". Sometime around 1952/53 the Canadian 221 Featherweight became a 221K. The "K"stands for "Kilbowie" where the machine hulls were produced.
Singer 222K Featherweights also had their hulls produced in Kilbowie and were assembled in Canada. Singer 222K Featherweights were never produced in the USA. Singer 222K production in Canada began in 1953 and had serial numbers that began with "EJ". Production ended in 1961 with serial numbers beginning with "ES". Very few, if any, 222K Featherweights were originally sold in the USA.
There were a few Singer 221 Featherweights from Canada that did not have their serial number begin with "E". All black Featherweights from Canada had serial numbers that began with "E" but the hard to find tan Singer 221 Featherweight sold in North America had serial numbers that began with "J". It was usually badged as "221J" (the "J" for St. Johns") but sometimes "221K". I highly doubt that the tan Featherweight had its hull produced in St. Johns, Quebec. Setting up the St. Johns manufacturing plant to produce a small number of machines would have been prohibitive. Tan machines were sold in the UK and in Canada. I suspect that the hulls were produced in Kilbowie specifically for the Canadian market with the serial numbers stamped beginning with "J" and then shipped to Canada to be assembled. Tan UK Featherweights are badged "221K" but have serial numbers that begin with "E".
All USA produced and Canadian assembled Featherweights have 100-120 volt motors and can be used in both the USA and Canada as the two countries have the same voltages.