In the late 1800s, the first fast foods were perhaps invented, they were wagons that would contain kitchen and everything to prepare a meal. They were called diners because they looked like the diners in a railroad car. These nice little rides brought the blue plate in the great depression of 1930s. Someone invented plates with three different compartments one for potatoes, meat and greens. Easy to use, easy to eat, easy to buy, it instantly became a hit in the lands. These plates were blue that is why the deal of a day is often called a blue plate special.
Now this term is often used in bistro’s, restaurants, cafe’s and nearly every food service. Since than America has been in love with these easy to eat meals and easy on the pocket too..