  Cities are engines of the knowledge-based economy, because they are the
primary sites of knowledge production activities that subsequently shape the
rate and direction of technological change and economic growth. Patents provide
a wealth of information to analyse the knowledge specialization at specific
places, such as technological details and information on inventors and entities
involved, including address information. The technology codes on each patent
document indicate the specialization and scope of the underlying technological
knowledge of a given invention. In this paper we introduce tools for portfolio
analysis in terms of patents that provide insights into the technological
specialization of cities. The mapping and analysis of patent portfolios of
cities using data of the Unites States Patent and Trademark Office (USPTO)
website (at http://www.uspto.gov) and dedicated tools (at
http://www.leydesdorff.net/portfolio) can be used to analyse the specialisation
patterns of inventive activities among cities. The results allow policy makers
and other stakeholders to identify promising areas of further knowledge
development and 'smart specialisation' strategies.

Digital Libraries