When was Matthew Cooper - American journalist born?

There isn't enough information to answer this question. There are multiple journalists named Matthew Cooper, and you need to be more specific.

For example, you could specify:

* Matthew Cooper, the American journalist who worked for Time magazine: This is likely the Matthew Cooper you are referring to, as he is the most prominent one. He was born on September 16, 1967.

Please provide more information so I can accurately answer your question.