Our exchange rate is just a price — the price of the dollar in terms of other currencies. It is not controlled by anyone. And a high price for the dollar, which is what we mean by a strong dollar, is not always desirable.She continues,
Such discussions would start with some basic economics. The desire to trade with other countries or invest in them is what gives rise to the market for foreign exchange. You need euros to travel in Spain or to buy a German government bond, so you need a way to exchange currencies.And this is the point, the exchange rate like any price just tells what the relative demand for the dollar is, but it doesn't tell us anything about whether this is a good or bad thing. The question that must be asked is, Why is the dollar "strong" or "weak"? The answer to this question will tell us if we should be worried about the state of the economy. The exchange rate is just a price, at best a signal of the underlying condition of the economy.
The supply of dollars to the foreign exchange market comes from Americans who want to buy goods, services or assets from abroad. The demand for dollars comes from foreigners who want to buy from the United States.
Anything that increases the demand for dollars or reduces the supply drives up the dollar’s price. Anything that lowers the demand for dollars or raises the supply causes the dollar to weaken.
Consider two examples. Suppose American entrepreneurs create many products that foreigners want to buy, and start many companies they want to invest in. That will increase the demand for dollars and so cause the dollar’s price to rise. Such innovation will also make Americans want to buy more goods and assets in the United States — and fewer abroad. The supply of dollars to the foreign exchange market will fall, further strengthening the dollar. This example describes very well the conditions of the late 1990s — when the dollar was indeed strong.
Now suppose the United States runs a large budget deficit that causes domestic interest rates to rise. Higher American interest rates make both foreigners and Americans want to buy more American bonds and fewer foreign bonds. Thus the demand for dollars increases and the supply decreases. The price of the dollar will again rise.
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Both developments — brilliant American innovation and troublesome American budget deficits — caused the dollar to strengthen. Yet one is clearly a positive for the American economy, the other a negative. The point is that there is no universal good or bad direction for the dollar to move. The desirability of any shift in the exchange rate depends on why the dollar is moving.