Singer sewing machines, which have been manufactured since 1851, feature serial numbers that can date a machine as far back as 1870. The Support and Resources section of the Singer company website has a machine serial number search feature that can determine the original fabrication date.
Singer machines built prior to 1900 have serial numbers with no letter prefix; those built after that year have serial numbers that begin with a one- or two-letter prefix. Between 1871 and 1899, Singer sewing machines had serial numbers between "611.000" and "16.831.099." Beginning in 1900, the machines were given prefixes of M, N and P. From 1924 onward, some machines were given double-letter prefixed serial numbers starting with AA, BA through BY, and JA.