U.S. became the top Bitcoin mining hub as China’s measured share hit zero

The United States became the largest identified center of Bitcoin mining in data released by the Cambridge Centre for Alternative Finance on October 13, 2021. The center estimated that U.S.-based operators supplied 35.4% of global Bitcoin hashrate at the end of August 2021, more than double their 16.8% share at the end of April.

The shift mattered because hashrate is the computing power competing to add blocks and secure Bitcoin's proof-of-work network. China had dominated Cambridge's geographic estimates since the dataset began in September 2019. The October 13 update showed that a state-directed shutdown in one jurisdiction had rapidly redrawn the industrial map of a network designed to operate without a central authority.

A new top three

Cambridge placed Kazakhstan second at 18.1%, up from 8.2% at the end of April, and the Russian Federation third at 11%, up from 6.8%. Together, the three countries represented 64.5% of the August estimate, a Coinburn calculation obtained by adding Cambridge's published country shares.

Declared mining activity in mainland China fell effectively to zero in July and August, according to data supplied by the participating pools. That contrasted with China's 75.53% share in September 2019, the first month in the Cambridge series.

The policy chronology preceded the data release. China's Financial Stability and Development Committee said in May 2021 that authorities would crack down on bitcoin mining and trading. Cambridge reported that global network hashrate then fell 38% in June. It rose 20% across July and August from the post-crackdown level, which the researchers interpreted as evidence that some equipment had been redeployed outside China. Those percentages describe changes in network computing power, not bitcoin's price or miners' revenue.

The October 13 record did not identify which machines moved, where individual firms settled or how much new U.S. capacity came from relocated Chinese equipment rather than previously planned expansion. The defensible conclusion was geographic: observed computing power had shifted, while the cause of every unit could not be traced.

What Cambridge actually measured

The mining map was an estimate, not a census of every facility. Cambridge derived country shares from geolocational data aggregated by BTC.com, Poolin, ViaBTC and Foundry. Its change log records that the October 13 update added observations from May through August 2021 and a chart of countries' absolute hashrate.

The model associated mining-pool connections with IP-derived locations and extrapolated the participating pools' sample to the whole network. Cambridge's maintained methodology lists the May-through-August sample at about 34% of total Bitcoin hashrate. That limitation is material: less than half of the network was observed directly, participating pools might not have been representative, and virtual private networks or proxy servers could make computing power appear in the wrong country.

Cambridge specifically warned that apparent shares for Ireland and Germany were probably inflated by redirected IP addresses. It therefore would be too strong to claim that every percentage point represented a physically verified mining site. The figures were the best available pool-based estimates under a disclosed method.

Why the U.S. lead changed the industry map

The result moved the institutional center of Bitcoin mining toward jurisdictions with different power markets, capital sources and regulatory systems. For U.S. miners and their suppliers, a 35.4% estimated share signaled that domestic infrastructure had become systemically important to the global network. For policymakers, it brought electricity use, grid effects and local oversight closer to home.

It did not mean the United States controlled Bitcoin. Miners competed across many firms and pools, and a country-level location estimate did not establish common ownership or coordinated behavior. Nor did China's zero observation prove that no concealed mining occurred anywhere in the country; it meant the participating pools declared no mainland Chinese hashrate for the measured months.

No event-day bitcoin price or trading-volume claim is included. The central October 13 development was measurable without one: Cambridge's delayed August observation documented a historic relocation of Bitcoin's productive infrastructure and placed the United States first for the first time in the series.