There are variations on this theme including one that is chocolate and made with cocoa powder. But according to my extensive research (a glance at Wikipedia), this raisin/spice version dates back to the Civil War.
On another positive note, I made the whole thing in one large saucepan! Easy clean up.
1 cup firmly packed brown sugar
1 1/2 cups water
1/3 cup vegetable oil
2 cups dark raisins
2 teaspoons cinnamon
1/2 teaspoon ground cloves
1/2 teaspoon nutmeg
1 teaspoon baking soda
1 teaspoon salt
2 teaspoons water (separate from the 1 1/2 cups above)
2 cups flour
1 teaspoon baking powder
Pre-heat oven to 325 degrees.
Combine sugar, water, vegetable oil, raisins and spices in a pan and bring to a boil. Boil for 3 minutes, stirring frequently. Let cool for 10 minutes.
Dissolve baking soda and salt in the 2 teaspoons of water and add to cooled raisin mixture. It will foam. If I'd paid more attention in science class I might be able to tell you why! (I'll bet Sheila knows.)
Blend in flour and baking powder and mix well.
Grease your pan (the recipe calls for a 9 inch square pan but it worked fine in my 8 inch square pan). Pour in batter and bake for 30 minutes (recipe says 55 minutes but mine was done at around the 30 minute mark. Better to check sooner than burn later...) Cake is done when the proverbial toothpick inserted into the center comes out clean. Don't over-bake.
Cool slightly before serving. Cover with your favorite frosting or dust with powdered sugar.