Final answer:
Three factors strongly influence a nation's level of trade: the size of its economy, its geographic location, and its history of trade.
Step-by-step explanation:
Three factors strongly influence a nation's level of trade: the size of its economy, its geographic location, and its history of trade. Large economies like the United States can do much of their trading internally, while small economies like Sweden have less ability to provide what they want internally and tend to have higher ratios of exports and imports to GDP. Nations that are neighbors tend to trade more, since costs of transportation and communication are lower. Moreover, some nations have long and established patterns of international trade, while others do not.