Across the Midwest (and farther afield) more than 1,000 coun

Across the Midwest (and farther afield) more than 1,000 counties in 26 states were .Across the Midwest (and farther afield) more than 1,000 counties in 26 states were declared natural-disaster areas—the largest such ruling that the US Department of Agriculture (USDA) has ever made. 请问破折号后面的成分中的such是指代前面的某个词还是就是such本身的意思啊?破折号后面属于什么结构?是such...that结构吗?