Every patent sits within a web of prior art. Citations connect new inventions to the knowledge they build upon, creating a vast network of technological lineage. The citation system also reveals the role of government funding in driving foundational research that later becomes the basis for commercial innovation.
Citations Per Patent Over Time
Average and median number of US patent citations per utility patent, by grant year.
The growth in backward citations reflects both the expanding knowledge base and changes in patent office practices encouraging more thorough prior art disclosure.
The average number of citations per patent has grown substantially over the decades, reflecting the expanding body of prior art that new inventions must acknowledge. The gap between average and median suggests a long tail of heavily-cited patents.
Citation Patterns
Citation Lag
Average and median time (in years) between a cited patent's date and the citing patent's grant date.
The lengthening citation lag shows that foundational knowledge has an increasingly long useful life, with modern patents reaching further back in time to reference prior art.
The citation lag -- how far back in time patents cite -- has been growing, indicating that the useful life of patented knowledge is extending. Modern patents draw on an increasingly deep well of prior art.
Government Funding
Government-Funded Patents Over Time
Number of utility patents acknowledging government funding interest, by year.
Government-funded patents consistently outperform private patents in citation impact, validating the role of public R&D investment in generating foundational innovations.
The Bayh-Dole ActBayh-Dole ActA 1980 US law that allowed universities and small businesses to retain patent rights from federally funded research, spurring academic patenting. of 1980 fundamentally changed the landscape of government-funded patenting by allowing universities and small businesses to retain rights to inventions developed with federal support. The resulting acceleration in government-acknowledged patents is clearly visible in the data, with recent years showing further growth as federal R&D budgets have expanded.
Top Government Funding Agencies
Agencies with the most associated patents (all time).
Federal agencies like DoD, DOE, and NIH fund research that leads to thousands of patents, often representing foundational technologies enabling subsequent waves of commercial innovation.
Government agencies -- particularly the Department of Defense, the Department of Energy, and the National Institutes of Health -- fund research that leads to thousands of patents each year. These government-interest patents often represent foundational technologies that enable subsequent waves of commercial innovation.
Citation Lag Analysis
How quickly does knowledge flow through the patent system? The citation lag -- the time between when a patent is granted and when it is cited by a subsequent patent -- measures the speed of knowledge diffusion. Shorter lags suggest faster uptake of ideas, while longer lags may indicate foundational work that takes years to be recognized.
Median Citation Lag Over Time
Median time (in years) between a cited patent's grant date and the citing patent's grant date.
The declining citation lag suggests knowledge is flowing faster through the patent system, likely driven by digital search tools that make prior art easier to discover.
Median Citation Lag by Technology Area
Median citation lag in years by CPC section and decade.
The increasing density of the citation network means that modern inventions build on a broader base of prior knowledge, accelerating the pace of cumulative innovation.
Corporate Citation Flows
How do major companies cite each other's patents? The chord diagramchord diagramA circular visualization showing flows or connections between entities. Arcs represent entities; ribbons connecting them represent directed flows (e.g., citation flows between companies). below maps directed citation flows between the top patent-filing organizations. Wider ribbons indicate more citations flowing from one company to another, revealing knowledge dependencies across the corporate landscape.
Decade:
Corporate Citation Network (2016-2025)
Directed citation flows between top patent filers. Arc size = total citations. Ribbon width = flow volume. Hover for details.
Citation flows reveal asymmetric knowledge dependencies. Some companies are primarily knowledge producers (heavily cited but cite few peers), while others are integrators (drawing broadly from multiple sources).
Technology Citation Leaders
Within each technology area, a few companies consistently receive the most citations from peers — these are the technology leaders whose patents form the foundation for subsequent innovation.
Citation Half-Life
How quickly do a company's patents accumulate their citations? The citation half-lifecitation half-lifeThe time it takes for a company's patents to accumulate half of their total forward citations. Shorter half-lives indicate more immediately impactful inventions; longer half-lives suggest foundational work. — the time to accumulate 50% of total citations — distinguishes companies whose patents have immediate vs. foundational impact.
Citation Half-Life by Company
Years until a company's patents accumulate 50% of their total forward citations. Only patents 15+ years old are included to ensure a full citation window.
Pharmaceutical and chemical companies tend to have longer citation half-lives, reflecting the slow but steady accumulation of citations in science-intensive fields. Electronics and IT companies show shorter half-lives, with citations peaking shortly after grant.
Citation data from PatentsView includes US patent citations only. Government interest is identified through the g_gov_interest table. Citation categories and lag calculations exclude records with missing dates. Citation lag is measured as the time between the cited patent's grant date and the citing patent's grant date. Corporate citation flows aggregate all citations between pairs of the top 30 assignees per decade. Citation half-life uses patents granted before 2010 to ensure at least 15 years of citation accumulation.