UPDATE 4:06 p.m. EST: The Dow ended the day above 20,000 after crossing the milestone for the first time ever Wednesday morning.
The Dow had flirted with topping the record high in the weeks following the U.S. presidential election. In the week since his inauguration, President Trump has signed a series of executive policy orders that have further encouraged traders.
“Clarity is the markets’ oxygen," Quincy Krosby, market strategist at Prudential Financial Inc., told Bloomberg.
All three major stock indices finished the day at fresh levels.
The Dow Jones Industrial Average, a measure of the stock market's performance, cracked 20,000 for the first time ever Wednesday morning. The Dow had come close to that number for weeks. CNN Money reports it increased 1,667 points since President Trump's election.
"Traders have been waiting for more details on infrastructure spending, and now they have it in a very clear format," Naeem Aslam, chief market analyst at Think Markets, told CNBC. "There is nothing bigger than this."
Trump was quick to tweet out his approval.
Days into his first week as president, Trump has signed a series of executive actions that demonstrate his seriousness about making good on business-friendly campaign policies like lower taxes and less regulation.
On Monday, he pulled the U.S. from the Trans-Pacific Partnership, a move many Republicans opposed since the party has traditionally supported free-trade agreements. On Tuesday, Trump gave the green light for construction of the Keystone XL and Dakota Access pipelines.
Trump has also met with business executives, both urging them to create more domestic jobs, but also promising them tax incentives for bringing business back to the U.S.
But the stock market rally has also been helped by sturdy economic growth under President Obama and the programs implemented by the Federal Reserve since the 2008 financial crisis. In 2016, U.S. wages posted their biggest rise in seven years.
Here's how stocks have reacted after past presidential inaugurations.
Stocks specifically tied to wall-building also saw a huge boost.
Bank stocks like JP Morgan Chase, Morgan Stanley and Goldman Sachs have been among the best-faring stocks in the post-election rally.
Still, the enthusiasm could run dry.
"We need open borders, open trade and open flow of capital. If we start going down this deglobalization road, this market is going to lose its euphoric underpins pretty quickly," Joe Quinlan, chief market strategist at U.S. Trust, told CNN Money.