in their archives. Submit via their online webform and expect a wait of three wweeks. Compose the entire story and submit on spec. This is not a query process. The stories usually relate to a personal experience by the writer and contain a typical beginning, middle and end with some sort of action involved . . . much like a short story. Several can be read at te website. Examples at the submissions page are:
-what happened when a writer shaved off his moustache
-what it's like to be colorblind, or a hypochondriac
-how an innocent ant farm turned into an unexpected lesson.
Oh yeah - it pays $1,000.
NOTE: You'll find an example of The Last Page column in each archived edition of The Smithsonian Magazine - all available online for free. They are simple and well-written. Study them well if for no other reason than to learn how to write visual, tight and clean.
DOUBLE NOTE: Had my head buried in research material on ebook publication. Dang! It's more complicated than I thought, though they try to make it sound so easy. If you take it seriously, you have to do your homework.