The focus of the research is on economic relations between Finland and the United States as well as their effects on the Finnish economy and Finnish-owned firms. A substantial share of the effects are transmitted through indirect channels. In the beginning the roles of the United States in world output, trade and foreign direct investment are evaluated. The role of the U.S. dollar as a world currency and the roles of the U.S. in the transmission of economic shocks and in trade policy are studied. The shocks analyzed include the financial crisis of the years 2007-2008 and changes in the exchange rate of the dollar. The NiGEM model of the international economy is used as the main analytic tool. Exports and imports of goods and services are studied at the aggregate level and according to product groups. The effects of Finlands U.S. exports are studied with an input-output model and with a macroeconomic model. Among investments, foreign direct investments as well as portfolio investments are considered. Economic relations are researched also at the firm level. The material includes annual reports of listed enterprises, the Orbis-databank on firms and a questionnaire posted to firms that are active on the U.S. market. Next, the importance of the United States in the innovation activity and technology transfer is explored. The effects on Finland are studied by focusing on e.g. studying in the U.S., patent co-operation and trade in high technology products, as well as with the help of the above-mentioned questionnaire. In the end of the book some conclusions from the whole study are drawn