In 2013 people living in the United States sold about $4.2 trillion worth of stuff to people living in other countries and bought about $4.2 trillion worth of stuff in return. What kind of stuff? All kinds. Residents of the United States (including firms operating in the United States) sold airplanes, bonds, wheat, and many other items to residents of other countries. Residents of the United States bought cars, stocks, oil, and many other items from residents of other countries.

How can we keep track of these transactions? In Chapter 22 we learned that economists keep track of the domestic economy using the national income and product accounts. Economists keep track of international transactions using a different but related set of numbers, the balance of payments accounts.

A country’s balance of payments accounts are a summary of the country’s transactions with other countries for a given year.

To understand the basic idea behind the balance of payments accounts, let’s consider a small-scale example: not a country, but a family farm. Let’s say that we know the following about how last year went financially for the Costas, who own a small artichoke farm in California:

How could we summarize the Costas’ transactions for the year? One way would be with a table like Table 34-1, which shows sources of cash coming in and uses of cash going out, characterized under a few broad headings. The first row of Table 34-1 shows sales and purchases of goods and services: sales of artichokes; purchases of groceries, heating oil, that new car, and so on. The second row shows interest payments: the interest the Costas received from their bank account and the interest they paid on their mortgage. The third row shows loans and deposits: cash coming in from a loan and cash deposited in the bank.

In each row we show the net inflow of cash from that type of transaction. So the net in the first row is −$10,000, because the Costas spent $10,000 more than they earned. The net in the second row is −$9,500, the difference between the interest the Costas received on their bank account and the interest they paid on the mortgage. The net in the third row is $19,500: the Costas brought in $25,000 with their new loan but put only $5,500 of that sum in the bank.

The last row shows the sum of cash coming in from all sources and the sum of all cash used. These sums are equal, by definition: every dollar has a source, and every dollar received gets used somewhere. (What if the Costas hid money under the mattress? Then that would be counted as another “use” of cash.)

A country’s balance of payments accounts is a table which summarizes the country’s transactions with the rest of the world for a given year in a manner very similar to the way we just summarized the Costas’ financial year.

Table 34-2 shows a simplified version of the U.S. balance of payments accounts for 2013. Where the Costa family’s accounts show sources and uses of cash, a country’s balance of payments accounts show payments from foreigners—sources of cash for the United States as a whole—and payments to foreigners—uses of cash for the United States as a whole.

Row 1 of Table 34-2 shows payments that arise from U.S. sales to foreigners and U.S. purchases from foreigners of goods and services in 2013. For example, the number in the second column of row 1, $2,280 billion, incorporates items such as the value of U.S. wheat exports and the fees foreigners pay to U.S. consulting companies in 2013. The number in the third column of row 1, $2,756 billion, incorporates items such as the value of U.S. oil imports and the fees U.S. companies pay to Indian call centers—the people who often answer your 1-800 calls—in 2013.

Row 2 shows U.S. factor income in 2013—the income that foreigners paid to American residents for the use of American-owned factors of production, as well as income paid by Americans to foreigners for the use of foreign-owned factors of production. Factor income mostly consists of investment income, such as interest paid by Americans on loans from overseas, profits of American-owned corporations that operate overseas, and the like. For example, the profits earned by Disneyland Paris, which is owned by the U.S.-based Walt Disney Company, are included in the $780 billion figure in the second column of row 2. The profits earned by the U.S. operations of Japanese auto companies are included in the $580 billion figure shown in the third column of row 2. Factor income also includes some labor income. For example, the wages of an American engineer who works temporarily on a construction site in Dubai are counted in the $780 billion figure in the second column.

Row 3 shows international transfers for the U.S. in 2013—funds sent by American residents to residents of other countries and vice versa. The figure in the second column of row 3, $118 billion, includes payments sent home by skilled American workers who work abroad. The third column accounts for the major portion of international transfers. The figure there, $242 billion, is composed mainly of remittances that immigrants who reside in the United States, such as the millions of Mexican-born workers employed in the United States, send to their families in their country of origin. In addition there is also a lot of money sent home by U.S. skilled workers abroad.

Row 4 of the table contains payments accruing from sales and purchases of assets between American residents and foreigners in 2013. For example, in 2013 Shanghui, a Chinese food company, purchased Smithfield Foods, America’s top pork packager, for $4.7 billion. As a payment to the American owners of Smithfield Foods for the purchase of their assets, that $4.7 billion is included in the figure $1,018 billion, found in the second column of row 4. Also in 2013, some major Wall Street firms were buying European debt, both private and public. As a payment by American residents to foreigners for the purchase of foreign assets, these purchases are included in the −$645 billion figure located in the third column of row 4.

In laying out Table 34-2, we have separated rows 1, 2, and 3 into one group, to distinguish them from row 4. This reflects a fundamental difference in how these two groups of transactions affect the future. When a U.S. resident sells a good such as wheat to a foreigner, that’s the end of the transaction. But a financial asset, such as a bond, is different. Remember, a bond is a promise to pay interest and principal in the future. So when a U.S. resident sells a bond to a foreigner, that sale creates a liability: the U.S. resident will have to pay interest and repay principal in the future. The balance of payments accounts distinguish between transactions that don’t create liabilities and those that do.

Transactions that don’t create liabilities are considered part of the balance of payments on current account, often referred to simply as the current account: the balance of payments on goods and services plus net international transfer payments and factor income. This corresponds to rows 1, 2, and 3 in Table 34-2. In practice, row 1 of Table 34-2, amounting to −$476 billion in 2013, corresponds to the most important part of the current account: the balance of payments on goods and services, the difference between the value of exports and the value of imports during a given period.

If you read news reports on the economy, you may well see references to another measure, the merchandise trade balance, sometimes referred to as the trade balance for short. It is the difference between a country’s exports and imports of goods alone—not including services. Economists sometimes focus on the merchandise trade balance, even though it’s an incomplete measure, because data on international trade in services aren’t as accurate as data on trade in physical goods, and they are also slower to arrive.

Transactions that involve the sale or purchase of assets, and therefore do create future liabilities, are considered part of the balance of payments on financial account, or the financial account for short, for a given period. This corresponds to row 4 in Table 34-2, which was $373 billion in 2013. (Until a few years ago, economists often referred to the financial account as the capital account. We’ll use the modern term, but you may run across the older term.)

So how does it all add up? The shaded rows of Table 34-2 show the bottom lines: the overall U.S. current account and financial account for 2013. As you can see, in 2013 the United States ran a current account deficit: the amount it paid to foreigners for goods, services, factors, and transfers was more than the amount it received. Simultaneously, it ran a financial account surplus: the value of the assets it sold to foreigners was more than the value of the assets it bought from foreigners.

In the 2013 official data, the U.S. current account deficit and financial account surplus didn’t exactly offset each other: the financial account surplus in 2013 was $27 billion smaller than the current account deficit. But that’s just a statistical error, reflecting the imperfection of official data. (The discrepancy may have reflected foreign purchases of U.S. assets that official data somehow missed.) In fact, it’s a basic rule of balance of payments accounting that the current account and the financial account must sum to zero:

or

CA = −FA

Why must Equation 34-1 be true? We already saw the fundamental explanation in Table 34-1, which showed the accounts of the Costa family: in total, the sources of cash must equal the uses of cash. The same applies to balance of payments accounts. Figure 34-1, a variant on the circular-flow diagram we have found useful in discussing domestic macroeconomics, may help you visualize how this adding up works. Instead of showing the flow of money within a national economy, Figure 34-1 shows the flow of money between national economies.

Money flows into the United States from the rest of the world as payment for U.S. exports of goods and services, as payment for the use of U.S.-owned factors of production, and as transfer payments. These flows (indicated by the lower green arrow) are the positive components of the U.S. current account. Money also flows into the United States from foreigners who purchase U.S. assets (as shown by the lower green arrow)—the positive component of the U.S. financial account.

At the same time, money flows from the United States to the rest of the world as payment for U.S. imports of goods and services, as payment for the use of foreign-owned factors of production, and as transfer payments. These flows, indicated by the upper yellow arrow, are the negative components of the U.S. current account. Money also flows from the United States to purchase foreign assets, as shown by the upper green arrow—the negative component of the U.S. financial account. As in all circular-flow diagrams, the flow into a box and the flow out of a box are equal. This means that the sum of the yellow and green arrows going into the United States (the top two arrows) is equal to the sum of the yellow and green arrows going out of the United States (the bottom two arrows) That is,

Equation 34-2 can be rearranged as follows:

Equation 34-3 is equivalent to Equation 34-1: the current account plus the financial account—both equal to positive entries minus negative entries—is equal to zero.

But what determines the current account and the financial account?

A country’s financial account measures its net sales of assets to foreigners. There is, however, another way to think about the financial account: it’s a measure of capital inflows, of foreign savings that are available to finance domestic investment spending.

What determines these capital inflows?

Part of our explanation will have to wait for a little while because some international capital flows are carried out by governments and central banks, which sometimes act very differently from private investors. But we can gain insight into the motivations for capital flows that are the result of private decisions by using the loanable funds model we developed in Chapter 25. In using this model, we make two important simplifications:

Figure 34-2 recaps the loanable funds model for a closed economy. Equilibrium corresponds to point E, at an interest rate of 4%, where the supply of loanable funds curve, S, intersects the demand for loanable funds curve, D. But if international capital flows are possible, this diagram changes and E may no longer be the equilibrium. We can analyze the causes and effects of international capital flows using Figure 34-3, which places the loanable funds market diagrams for two countries side by side.

Figure 34-3 illustrates a world consisting of only two countries, the United States and Britain. Panel (a) shows the loanable funds market in the United States, where the equilibrium in the absence of international capital flows is at point E_US with an interest rate of 6%. Panel (b) shows the loanable funds market in Britain, where the equilibrium in the absence of international capital flows is at point E_B with an interest rate of 2%.

Will the actual interest rate in the United States remain at 6% and that in Britain at 2%? Not if it is easy for British residents to make loans to Americans. In that case, British lenders, attracted by high U.S. interest rates, will send some of their loanable funds to the United States. This capital inflow will increase the quantity of loanable funds supplied to American borrowers, pushing the U.S. interest rate down. At the same time, it will reduce the quantity of loanable funds supplied to British borrowers, pushing the British interest rate up. So international capital flows will narrow the gap between U.S. and British interest rates.

Let’s further suppose that British lenders regard a loan to an American as being just as good as a loan to one of their own compatriots, and American borrowers regard a debt to a British lender as no more costly than a debt to an American lender. In that case, the flow of funds from Britain to the United States will continue until the gap between their interest rates is eliminated. In other words, when residents of the two countries believe that a foreign asset is as good as a domestic one and that a foreign liability is as good as a domestic one, then international capital flows will equalize the interest rates in the two countries.

Figure 34-4 shows an international equilibrium in the loanable funds markets where the equilibrium interest rate is 4% in both the United States and Britain. At this interest rate, the quantity of loanable funds demanded by American borrowers exceeds the quantity of loanable funds supplied by American lenders. This gap is filled by “imported” funds—a capital inflow from Britain. At the same time, the quantity of loanable funds supplied by British lenders is greater than the quantity of loanable funds demanded by British borrowers. This excess is “exported” in the form of a capital outflow to the United States. And the two markets are in equilibrium at a common interest rate of 4%—at that interest rate, the total quantity of loans demanded by borrowers across the two markets is equal to the total quantity of loans supplied by lenders across the two markets.

In short, international flows of capital are like international flows of goods and services. Capital moves from places where it would be cheap in the absence of international capital flows to places where it would be expensive in the absence of such flows.

The open-economy version of the loanable funds model helps us understand international capital flows in terms of the supply and demand for funds. But what underlies differences across countries in the supply and demand for funds? Why, in the absence of international capital flows, would interest rates differ internationally, creating an incentive for international capital flows?

International differences in the demand for funds reflect underlying differences in investment opportunities. In particular, a country with a rapidly growing economy, other things equal, tends to offer more investment opportunities than a country with a slowly growing economy. So a rapidly growing economy typically—though not always—has a higher demand for capital and offers higher returns to investors than a slowly growing economy. As a result, capital tends to flow from slowly growing to rapidly growing economies.

The classic example, described in the upcoming Economics in Action, is the flow of capital from Britain to the United States, among other countries, between 1870 and 1914. During that era, the U.S. economy was growing rapidly as the population increased and spread westward and as the nation industrialized. This created a demand for investment spending on railroads, factories, and so on. Meanwhile, Britain had a much more slowly growing population, was already industrialized, and already had a railroad network covering the country. This left Britain with savings to spare, much of which were lent out to the United States and other New World economies.

International differences in the supply of funds reflect differences in savings across countries. These may be the result of differences in private savings rates, which vary widely among countries. For example, in 2010 gross private savings were 28.5% of Japan’s GDP but only 19.2% of U.S. GDP. They may also reflect differences in savings by governments. In particular, government budget deficits, which reduce overall national savings, can lead to capital inflows.

The loanable funds model helps us understand the direction of net capital flows—the excess of inflows into a country over outflows, or vice versa. The direction of net flows, other things equal, is determined by differences in interest rates between countries. As we saw in Table 34-2, however, gross flows take place in both directions: for example, the United States both sells assets to foreigners and buys assets from foreigners. Why does capital move in both directions?

The answer to this question is that in the real world, as opposed to the simple model we’ve just learned, there are other motives for international capital flows besides seeking a higher rate of interest.

Individual investors often seek to diversify against risk by buying stocks in a number of countries. Stocks in Europe may do well when stocks in the United States do badly, or vice versa, so investors in Europe try to reduce their risk by buying some U.S. stocks, as investors in the United States try to reduce their risk by buying some European stocks. The result is capital flows in both directions.

Meanwhile, corporations often engage in international investment as part of their business strategy—for example, auto companies may find that they can compete better in a national market if they assemble some of their cars locally. Such business investments can also lead to two-way capital flows, as, say, European car makers build plants in the United States even as U.S. computer companies open facilities in Europe.

Finally, some countries, including the United States, are international banking centers: people from all over the world put money in U.S. financial institutions, which then invest many of those funds overseas.

The result of these two-way flows is that modern economies are typically both debtors (countries that owe money to the rest of the world) and creditors (countries to which the rest of the world owes money). Due to years of both capital inflows and outflows, at the end of 2013, the United States had accumulated foreign assets worth $23.7 trillion, and foreigners had accumulated assets in the United States worth $29.1 trillion.