The earliest running blockchain is actually Surety's blockchain, which was created in 1995 by Stuart Haber and Scott Stornetta. Surety's private blockchain was designed to timestamp digital documents as proof of existence.
Though not widely known, Surety's blockchain predates the public Bitcoin blockchain by over a decade and is published in The New York Times. Bitcoin's blockchain was launched in 2009 and became the first widely adopted public permissionless blockchain.