In its 2007 global competitiveness index, the Swiss-based Forum said the sheer size of the US market made it "arguably the country with the most productive and innovative potential in the world."
This was in spite of Washington's huge budget and trade deficits and the erosion of the US dollar that have caused many to question whether the long-time economic leader was losing ground to emerging players India and China.
While it ranked first overall among 131 countries -- fending off Switzerland, Denmark, Sweden and Germany in the top five -- the United States scored 75th for macroeconomic stability, behind developing countries including Tunisia, Vietnam and Mongolia.
In addition to concerns over the rising US public debt, the report also flagged questions about the government's ability to maintain arms-length relationships with the private sector and avoid favouritism in its policy-making.
"These are areas that require attention from the authorities to ensure that the country maintains its competitive edge going into the future," it concluded.
Singapore and Japan were the top-ranked Asian countries in the index, in seventh and eighth place. The largest markets in the region, China and India, placed 34th and 48th respectively.
Chile, ranked 26th, was named the most competitive Latin American economy. Mexico placed 52nd, Brazil was 72nd and Argentina ranked what the Forum called "a disappointing 85th."
The WEF changed its way of calculating countries' competitiveness in 2007, making direct comparisons with prior rankings impossible.
After recalculating last year's list to reflect those changes -- which include expanded analysis of financial, labour and goods markets, and a new emphasis on market size -- it said the United States had also ranked first in 2006, followed by Britain, Denmark, Switzerland and Japan.
The United States had originally been ranked sixth last year, in an announcement that sparked spirited debate on Capitol Hill and aggravated tensions between trade partners Washington and Beijing. At the time, the Forum had deemed Switzerland the world's most competitive economy.
In the 2007 index, Israel was the top-ranked Middle Eastern country, in 17th place, followed by oil exporters Kuwait and Qatar who were ranked 30th and 31st ahead of Saudi Arabia at 35.
Resurgent economic growth in sub-Saharan Africa is "not yet reflected in improved competitiveness rankings for the region," the Forum said. South Africa, ranked 44th overall, had the continent's best showing, followed by Mauritius in 60th.
Sub-Saharan African countries including Mozambique, Zimbabwe and Burundi dominated the very bottom of the ranking. Chad was rated lowest, in 131st and last place