"The word 'ketchup' conjures up an image of the thick, sweet, tomato-based condiment...Americans did not invent ketchup, which was not thick, sweet, or made from tomatoes...British explorers, colonists, and traders came into contact with the sauce in Southeast Asia, and upon their return to Europe they attempted to duplicate it. As soybeans were not grown in Europe, British cooks used such substitutes as anchovies, mushrooms, walnuts, and oysters. British colonists brought ketchup to North Ameirca, and Americans continued experimenting, using a variety of additional ingredients, including beans and apples. Tomato ketchup may have originated in America. It was widely used throughout the United States in the early nineteenth century, and small quantities of it were first bottled in the 1850s. After the Civil War commercial production of ketchup rapidly increased...tomato ketchup became the most important version...In 1896 the New York Tribune reported that tomato ketchup was America's national condiment...Up until 1900, ketchup was mainly used as an ingredient for savory pies and sauces, and to enhance the flavor of meat, poultry, and fish. It then became famous as a condiment following the appearance of three major host foods: hamburgers, hot dogs, and french fries."
---Oxford Encyclopedia of Food and Drink in America, Andrew F. Smith [Oxford University Press:New York] 2004, volume 2(p. 5-6)