Metropolitan areas with population densities of about 4,000 people per square mile tend to produce the highest rate of patenting, according to a recent article in the American Journal of Economics and Sociology. In a study of U.S. metro areas over a ten-year period, the authors found that metro population density has a significant positive correlation with patenting rates.

Invention is a driver of economic growth. That is the assertion of Brookings latest report on U.S. patenting and its effect on the country's economic prosperity entitled Patenting Prosperity: Invention and Economic Performance in the United States and its Metropolitan Areas. The U.S.'s innovative capacity and activity has increased steadily, but other nations are catching up and the U.S. must identify the implications of this fact to remain competitive.

Two recent academic research articles found that innovation at institutions of higher education and domestic firms are significantly impacted by an increase in the immigration of skilled and qualified immigrants. An article from Stuen et al. found the quality of immigrant students was the determining factor in their contribution to the production of knowledge at academic science and engineering laboratories. In an unpublished article from Kerr et al., the authors examined the impact of skilled immigrants on the employment structures and innovation rates of U.S. firms.

A central tenet in the understanding of regional economic clusters is the idea that the closer two actors are to one another, the more likely they are to collaborate. This belief is based on decades of research done to examine knowledge spillovers and the effect of spatial proximity on tacit knowledge sharing. In a recent article, however, Jasjit Singh of INSEAD and Matt Marx of MIT differentiate the varying effects of crude distance on knowledge sharing compared to the effects of geopolitical borders.