Records show that lettuce have been cultivated in Egypt back in the 2680s BC, and they were grown mainly fortheir seeds to make oil. But then lettuce started taking on other meanings for the Egyptians, including religious meanings.
The early lettuce in Egypt were leafy and tall, about 30 inches high. No iceberg lettuce for the Egyptians. If they had that kind of lettuce around, they probably would have start planting them!
The Egyptians passed on the lettuce to the Greeks (perhaps when Alexandra the Great conquered them), and the Greeks passed on the lettuce to the Romans (perhaps when the Romans conquered them!). It was the Romans that named this plant "lactura" ("lac" meaning "milk," referring to a milky-like substance that came out of the stems of the lettuce). The Anglos adopted the word lactura and put their middle English twang to it, calling it "lettuce."
This leafy veggie was introduced in North America by Christopher Columbus in the late 1490s AD.
Since lettuce has such a short life span (heck, it's like when you buy them at the store, they start going bad before you get home!), you were only able to buy them at a close market. Pretty much, if you didn't have a farmer's market in town that sold them, then you just wouldn't get any lettuce. There was no way you could grow lettuce across the country and ship them without them soiling.
However, during the 1900s, the U.S. started developing packaging techniques to ship these veggies to distant places. During the 1950s, the U.S. finally developed a cooling and packaging technique for lettuce so that you could ship them from New York to Florida without them going bad. Or from North Carolina to California...whatever!
There are different kinds of lettuce. The iceberg lettuce is considered a "crisphead" type. Then you have your more nutrient-dense Romaine variety. Besides the appearances, the main things that distinguishes these varieties of lettuce is the nutritional content. In general, all lettuce are high in vitamin A and potassium. Romaine, however, is VERY high in vitamin A since the leafs are so dark green. Romaine is also high in calcium. But get this: Romaine also has protein! But not just any protein, but "complete protein," meaning that it has all the essential amino acids that the body cannot produce on its own.
Iceberg lettuce is perhaps the least nutrient-dense lettuce. This doesn't mean it's useless! If anything, it has a HIGH water content, so if you eat enough of these, then you'll be getting plenty of water to meet your daily water intake needs. Okay...well...you probably won't eat that much of this lettuce. But as far as nutrition goes, it has vitamin A and potassium, as well as fiber and small amounts of vitamin C.