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Port of Rotterdam, Netherlands

Satellite surveillance of the largest port in Europe measures container traffic, storing or stacking of raw materials like iron ore, or the number of vessels at port. Taking it all together, analysts can estimate the port's revenue growth, and can develop macro-economic indicators of the health of the European economy.

By peering down on all the world's major ports, analysts can do the same for the health of the global economy. Under constant surveillance are the ports of Long Beach, CA, Shanghai, Singapore, and Dubai, among others.