The focus on aggregate national accounting began with the Bretton Woods Conference, which established the International Monetary Fund (IMF) and the World Bank. These institutions required a uniform metric to assess the economic health of member nations, determine subscription quotas, and evaluate creditworthiness for loans.

Initially, Gross National Product (GNP) was used — measuring the total value of goods and services produced by a country’s citizens, regardless of where that production physically occurred. In an era of regulated capital flows, residency of ownership was the meaningful unit.

The collapse of the gold-standard Bretton Woods system in 1971 led to the 1974 agreement between the United States and Saudi Arabia. This established the Petrodollar system, ensuring that oil — the world’s most vital commodity — was priced and traded exclusively in U.S. dollars.

GDP became the tool to measure this internal “engine” of production — not wealth in the abstract, but the throughput of the domestic economy that could generate dollar-earning exports or attract dollar-denominated investment.

The United States formally adopted GDP as its primary output measure in 1991, aligned with the peak of petrodollar-led globalisation. Three structural forces drove the change:

• Foreign Direct Investment (FDI) — As multinationals moved production across borders, GNP misrepresented a host country’s actual economic activity. GDP captures the output of foreign firms operating locally.
• Debt Servicing — For developing nations holding dollar-denominated debt, GDP is a more relevant measure of the tax base and capacity to service obligations.
• Energy Consumption Correlation — GDP correlates more tightly with domestic energy use than GNP, making it a better proxy for a nation’s demand for oil, and therefore for petrodollars.

The System of National Accounts (SNA), maintained by the United Nations, provides the international standard for GDP calculation. This standardisation allows global investors and the IMF to compare the “output density” of different geographic regions.

In a world where the dollar is the unit of account for trade, GDP provides a standardised denominator for measuring debt-to-GDP ratios — essential for sovereign bond markets — and trade balances denominated in USD, requiring a domestic output metric to assess economic sustainability.