easily melted, shaped, and measured made it a natural trading asset. Beginning in the late 10th century, commodity markets grew as a mechanism for allocating goods, labor, land and capital across Europe. Between the late 11th and the late 13th century, English urbanization, regional specialization, expanded and improved infrastructure, the increased use of coinage and the proliferation of markets and fairs were evidence of commercialization. The spread of markets is illustrated by the 1466 installation of reliable scales in the villages of Sloten and Osdorp so villagers no longer had to travel to Haarlem or Amsterdam to weigh their locally produced cheese and butter. The Amsterdam Stock Exchange, often cited as the first stock exchange, originated as a market for the exchange of commodities. Early trading on the Amsterdam Stock Exchange often involved the use of very sophisticated contracts, including short sales, forward contracts, and options. "Trading took place at the Amsterdam Bourse, an open aired venue, which was created as a commodity exchange in 1530 and rebuilt in 1608. Commodity exchanges themselves were a relatively recent invention, existing in only a handful of cities." In 1864, in the United States, wheat, corn, cattle, and pigs were widely traded using standard instruments on the Chicago Board of Trade (CBOT), the world's oldest futures and options exchange. Other food commodities were added to the Commodity Exchange Act and traded through CBOT in the 1930s and 1940s, expanding the list from grains to include rice, mill feeds, butter, eggs, Irish potatoes and soybeans. Successful commodity markets require broad consensus on product variations to make each commodity acceptable for trading, such as the purity of gold in bullion. Classical civilizations built complex global markets trading gold or silver for spices, cloth, wood and weapons, most of which had standards of quality and timeliness. Through the 19th century "the exchanges became effective spokesmen for, and innovators of, improvements in transportation, warehousing, and financing, which paved the way to expanded interstate and international trade." Reputation and clearing became central concerns, and states that could handle them most effectively developed powerful financial centers. Commodity price index In 1934, the U.S. Bureau of Labor Statistics began the computation of a daily Commodity price index that became available to the public in 1940. By 1952, the Bureau of Labor Statistics issued a Spot Market Price Index that measured the price movements of "22 sensitive basic commodities whose markets