Look at the date code stamp on the barrel, see related link.
The Remington Wingmaster with the serial number 2039814 was manufactured in 1980. Remington's serial number system can help date their shotguns, and this particular number falls within the range indicating production during that year.
100-350 USD
Made by the Remigton Firearms Company.
Serial 718943w
Check this table for the answer: http://www.remingtonsociety.com/rsa/questions/barrelcodes
They are all still made in Illion, New York, I believe.
Do a search on barrel codes, I believe that will give you an answer
Remingtons are dated by a letter code on the left side of the barrel, not the Serial number.
The W ahead of the serial number indicates that your Remington 870 wingmaster was made in 1972.
Check this table for the answer: http://www.remingtonsociety.com/rsa/questions/barrelcodes
Remingtons are usually dated not be serial number but by a 2 or 3 LETTER code on the left side of the barrel. See Remington Collectors Assoc. website for a chart.
http://remingtonsociety.com/rsa/questions/barrelcodes