The latest data available on the state distribution of R&D performance are for 1995. These data cover R&D performance by industry, academia, and Federal agencies, along with the federally funded R&D activities of nonprofit institutions. The state data on R&D contains 52 records: the 50 states, the District of Columbia (DC), and "other/unknown" which accounts for R&D in Puerto Rico and other non-state U.S. regions, as well as R&D for which the particular state was not known. Approximately two-thirds of the R&D that could not be associated with a particular state is R&D performed by the nonprofit sector. Consequently, the distribution of R&D by state indicates primarily where R&D is undertaken in Federal, industrial, and university facilities.
In 1995, total R&D expenditures in the United States were $183 billion, of which $177 billion could be attributed to expenditures within individual states, with the remainder falling under an undistributed, "other/unknown" category. (See appendix table B-8.) The statistics and discussion below refer to state R&D levels in relation to the distributed total of $177 billion.
R&D is substantially concentrated in a small number of states. In 1995, California had the highest level of R&D expendituresover $36 billionrepresenting approximately one-fifth of the $177 billion U.S. total. The six states with the highest levels of R&D expendituresCalifornia, Michigan, New York, Massachusetts, New Jersey, and Texas (in descending order)accounted for approximately one-half of the entire national effort. The top 10 statesadding, in descending order, Illinois, Pennsylvania, Maryland, and Ohioaccounted for nearly two-thirds of the national effort (figure 14 and text table 7). California's R&D effort exceeded, by nearly a factor of three, the next-highest state, Michigan, with $13 billion in R&D expenditures. After Michigan, R&D levels declined relatively smoothly to approximately $5 billion for Ohio. The 20 highest-ranking states in R&D expenditures accounted for about 85 percent of the U.S. total; the lowest 20 states, for 5 percent.
States that are highest in total R&D performance are usually ranked among the highest in both industrial and academic R&D performance. For example, among the top 10 for total R&D, eight states were among the top 10 for industrial R&D, and eight were among the top 10 for academic R&D, as shown in table 7.
For Federal intramural research, there was less com-monality with the top 10 for total R&D. Only four states were found in both top-10 lists: Maryland, California, Ohio, and Texas. The six others in the Federal intramural list, in descending order of Federal R&D performance, were the District of Columbia, Virginia, Alabama, Florida, New Mexico, and New Jersey. Maryland ranked first among Federal R&D performers, followed by the District of Columbia, California, and Virginia. The placement of Maryland, the District of Columbia, and Virginia among the top four in Federal R&D performance reflects the concentration of Federal facilities and administrative offices within the national-capital area. Alabama, Florida, and New Mexico rank among the highest in Federal R&D because of their relatively high shares of Federal space- and defense-related R&D.
States vary widely in the size of their economies, owing to differences in population, land area, infrastructure, natural resources, and history. Consequently, variation in the R&D expenditure levels of states may simply reflect differences in economic size or the nature of their R&D efforts. A simple way of controlling for the size effect is to measure each state's R&D level as a proportion of its gross state product (GSP) (appendix table B-8). That proportion is referred to as R&D "intensity" or "concentration." Overall, the Nation's total R&D to gross domestic product ratio was 2.5 percent in 1995. The top 10 rankings for R&D intensity were, in descending order, New Mexico (8.1 percent), the District of Columbia, Michigan, Massachusetts, Maryland, Delaware, California, Connecticut, Rhode Island, and Idaho (the latter with an intensity of 3.5 percent). New Mexico's R&D intensity is largely attributable to Federal support to the Sandia National Laboratories and Los Alamos National Laboratory FFRDCs in the state, provided by the Department of Energy.
Figure 15 juxtaposes state R&D performance with GSP, with the 50 states and the District of Columbia ranked in descending order of R&D. R&D expenditures are displayed as a dark bar, measured on the upper axis; GSP is displayed as a wider gray bar measured on the lower axis; both are measured in billions of dollars. The two highest-ranked states in total R&DCalifornia and Michiganclearly show R&D levels that are relatively high in relation to their GSPs, as reflected by their presence in the top 10 list for R&D intensity (table 7).
 Although annual data are available on the location of R&D performance by the academic and Federal sectors, NSF conducts surveys on the State distribution of industrial R&D performance only in odd-numbered years. At this writing, the 1997 industry R&D survey data have not been processed, making 1995 the most recent year for which the State-specific R&D totals can be reported.
 R&D performance data include the R&D activities in FFRDCs in each sector of the economy. For a more detailed description of these data, as well as comparisons of 1985 R&D expenditures with other economic measures (for example, population and gross state product), see NSF, Geographic Patterns: R&D in the United States, by John E. Jankowski, NSF 89-317 (Washington, DC, 1989).
 Federal intramural performance included the administration of extramural R&D programs.
 For additional information about the geographic distribution of R&D within the United States, see National Science Foundation, Science and Engineering State Profiles: 1997, by Richard J. Bennof and Steven Payson, NSF 98-315 (Arlington, VA, 1998).