The U.S. current account trade deficit narrowed slightly in the April-June quarter, reflecting gains in exports of oil and civilian aircraft and a bigger surplus in Americans' overseas investment earnings.

The deficit in the current account shrank to $98.5 billion in the second quarter, down 3.5 percent from the revised $102.1 billion deficit in the January-March period, the Commerce Department reported Wednesday.

It was the smallest current account deficit since an imbalance of $87.3 billion in the final three months of last year. The lower deficit reflected a variety of factors including gains in U.S. exports and a larger surplus in earnings by Americans in their overseas investments.

The current account is the broadest measure of trade, covering not only the flow of goods and services but also investment flows.

Economists carefully track the current account deficit because it is a measure of how much foreign financing the country needs. The second quarter deficit represented 2.3 percent of total economic output, as measured by the gross domestic product, down from 2.4 percent in the first quarter. The highest deficit as a percentage of GDP was 6.3 percent set in the fourth quarter of 2005.

The quarterly deficits regularly topped $150 billion in the four years before the Great Recession of 2007-2009. The downturn cut into domestic demand and pushed the deficits lower.

The U.S. has benefited from a boom in oil and gas production, mostly because new drilling technologies have made it feasible to drill for oil and gas in states such as North Dakota, New York and Pennsylvania.

That has pushed down the trade deficit by boosting petroleum exports and also reducing U.S. dependence on foreign oil.