Portland is the largest city in the U.S. state of Oregon and the seat of Multnomah County. It is Portland's access to the Pacific Ocean via the Willamette and the Columbia rivers, as well as its easy access to the agricultural Tualatin Valley via the "Great Plank Road" (the route of current-day U.S. Route At around 15° S near the Australian coast the SEC divides forming the southward flow of the EAC. It is the largest ocean current close to the shores of Australia. The EAC reaches a maximum velocity at 30° S where its flow can reach 90 cm/s. The city of Chicago is located in northern Illinois, United States, at the south western tip of Lake covered by a warm inland sea (hundreds of millions of years before the glaciation of the Chicago area).