These rankings derive from Thomson Scientific’s Essential Science Indicators and are based on papers published and cited in Thomson-indexed journals between January 1996 and April 30, 2006. In addition to comparing the U.S. facilities against one another, the rankings also show each institution’s world rank in the given field, based on the extensive institutional listings (featuring the top 1% most-cited institutions worldwide in each field) in Essential Science Indicators.

Of the institutions listed here, the National Cancer Institute (NCI) makes a particularly strong showing, appearing in 6 of the 11 tables and grabbing the #1 spot in two fields, Molecular Biology & Genetics and Biology & Biochemistry. Los Alamos National Laboratory also takes six spots, including a #1 appearance in Physics, while the U.S. Navy garners an equal number of placements. The "U.S. Navy" designation, it should be noted, covers a variety of facilities, notably the Naval Research Laboratory in Washington, D.C. Numerous separate sites are also included among the medical centers—numbering upwards of 170 nationwide—under the auspices of the Department of Veterans Affairs. Those sheer numbers undoubtedly helped the combined VA facilities in achieving five appearances here, including the #1 spot in Neuroscience & Behavior.

Size was also on the side of another organization that merits special mention, the U.S. Department of Agriculture. In two fields, Environment/Ecology and Plant & Animal Sciences, the USDA ranks not only first among U.S. government institutions but first in the world. In Immunology, the NCI and the National Institute of Allergy and Infectious Diseases (NIAID) also distinguished themselves in this regard, appearing within the top three spots in both the U.S.-government and the world rankings.