Mark Twain obtained three patents over his lifetime.
Notes on verification
Confirmed by USPTO records and multiple independent reputable sources (Smithsonian, History.com) with consistent patent numbers and descriptions. [tier=silver indep_score=0.875 clusters=2 claim_tier=notable | framework convergence=partial on US Patent Office historical records (upstreams: USPTO patent records) — publishers independent, evidence may not be | kind=empirical eligibility=high]
Sources
- Unswerving irregularity | USPTO (seed:firsts_and_inventions)
- https://www.smithsonianmag.com/history/mark-twains-patented-inventions-180958static/ (corroboration)
- https://www.history.com/news/mark-twain-inventor-patents (corroboration)