For academics and policymakers invested in regional economic development, two pertinent questions are how innovative city-regions rise and whether it is inevitable that innovative city-regions will fall. Using data from 8 million patents granted to U.S.-based inventors between 1850 and 1999, this study describes a general process that city-regions undergo as innovation begins, expands, declines and (sometimes) resurges in regions. The results of the study show that inventors experiment with a small number of promising, diverse and non-local ideas in the years before innovation in their home regions begins to grow, that inventors build on early locally introduced ideas as innovation in their home regions expands, and that inventors experiment with relatively homogeneous sets of ideas shortly before innovation in their home regions declines. The results also show that declining U.S. city-regions rarely experience second waves of local innovative growth. However, when they do experience second waves, those waves are anticipated by changes in the knowledge sourcing strategies of local inventors. In particular, the years leading up to second cycles of regional innovative growth, local inventors experiment with promising, diverse and non-local ideas.

中文翻译：

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区域创新增长周期

对于投资于区域经济发展的学者和政策制定者来说，两个相关的问题是创新城市区域如何崛起以及创新城市区域是否不可避免地会下降。本研究使用 1850 年至 1999 年间授予美国发明者的 800 万项专利的数据，描述了城市区域随着创新开始、扩大、下降和（有时）在区域内复苏而经历的一般过程。研究结果表明，在其家乡地区的创新开始增长之前的几年里，发明者尝试了少量有前途的、多样化和非本地的想法，发明者在其家乡地区的创新扩大时建立在早期本地引入的想法之上，并且发明者在其家乡地区的创新下降之前不久就尝试了相对同质的想法集。结果还表明，衰落的美国城市地区很少经历第二波地方创新增长。然而，当他们确实经历了第二波浪潮时，这些浪潮是由当地发明者的知识采购策略的变化所预料的。特别是在区域创新增长的第二个周期之前的几年，当地的发明者尝试了有前途的、多样化的和非当地的想法。