Greyhawk began it existence like many towns located along a river, as a trading town. For the City of Greyhawk their proximity to the great lake, the Nyr Dyv, made them a prime location for goods traveling from what would become the independent nations of Furyondy, Urnst, and Nyrond back to the heart of the Great Kingdom. Like may such towns in its early days money moved quickly into the town and just as quickly out.
Where the City of Greyhawk began to distinguish itself was in its textile mills. The mills made use of the abundance of cotton, wool, and leather being produced from Furyondy, Urnst, and Nyrond, and refined them into high valued textiles. These mills not only generated wealth for the developing city, but drew in workers from the surrounding area.
Next came the meat packing plants. Salt was imported from Wooly Bay in the south to help preserve the precious fish, mutton, pork, venison, and beef as they were shipped in barrels ever east to help satiate the ravenous appetites of the Great Kingdom. As these plants grew in influence a burgeoning hodgepodge of industries grew up around them. Cattle and pig farms were established nearby. A fishing industry boomed, and local hunters found a way to sell their unused meat before it spoiled. Slaughterhouses sprung up to help feed the meat packing plants and local butchers opened shop for meat the packing plants didn’t buy.
All was going well for the booming city until the Great Kingdom’s public works set about building a roadway that streamlined travel from its lucrative border states and bypassed the City of Greyhawk. With its position as a vital trade stop circumvented the City began to stagnate, and slowly shrink as workers followed jobs that were now moving elsewhere. This slow decline might have been the end of the City of Greyhawk had it not been for the rise of the adventuring caste.
The standard of living in the Flanaess had grown to such a level that people no longer found themselves fighting just to survive and began to look for trouble to get into. It was around that time treasures were found in the Cairn Hills to the east of the City and the adventuring caste came in droves to the City so that they could supply themselves and leave – often to never be seen again. Then treasure was found in the ruins of Castle Greyhawk and more adventurers came than ever before.
The City of Greyhawk’s leaders recognized this moment for what it was: an opportunity to secure the future of the City. They took the time to expand the trade portfolio of the city making it a center for precious metal and gem trades, while growing their presence in the textile and meat packing fields. They built up the City’s infrastructure, reformed its trade practices, encouraged self-sustaining businesses that would be able to continue on after the treasures dried up, and positioned themselves as the financial heart of the Flanaess.
 In the text, “. . . Gradually the town’s central location and high standard of living led to the creation of great textile mills in what is now the Slum Quarter of the Old City . . .” (Niles, 4)
 Both the textile mills and the meat packing plants are located in what is now known as the Slum Quarter. This is hardly surprising as often such industries are historically notorious for paying their works poorly and putting them into dangerous working conditions. Slums often spring up near such industries as their poorly paid works attempt to live as closely to work, as cheaply as possible.
 I’ve been unable to pinpoint an exact date. If anyone knows of one I would love to use it.
Niles, Douglas. Greyhawk: Gem of the Flanaess A gazetteer of the Free City of Greyhawk and the surrounding area. TSR, Inc. 1989. pg. 4