The Dow Jones Industrial Average rose 303.31 points to close at 21,115.55 following US President Donald Trump's address to Congress last night.
The S&P 500 index gained 32.32 points, rising to 2,395.96, while the tech-heavy Nasdaq Composite index was up 78.59 points at 5,904.03.
Shares have been climbing since Mr Trump's election victory after investor optimism about deregulation.
He has also promised to cut taxes and boost infrastructure spending.
Financial firms were the top gainers on the Dow, with JP Morgan Chase and American Express both up more than 2.3%.
Tom Stevenson from Fidelity International said the Dow Jones Index only cleared 20,000 points three weeks ago, making this the fastest rise between 1,000 milestones since 1999.
Sentiment was helped by comments suggesting that the US central bank may raise rates sooner rather than later.
A rate hike in March would make it more expensive to borrow money to buy stocks, but it would also signal the Fed's confidence in economic expansion after stagnation.
"It's not necessarily the rate increase that matters. It's that they're seeing things improving. If the Fed feels more confident, maybe we should too," said Warren West, principal at Greentree Brokerage Services in Philadelphia.
US shares have hit new highs on Wednesday.