The rally roared back to life after Trump signed numerous executive orders on Tuesday, including clearing the path for the construction of two oil pipelines to boost the energy industry.
The S&P 500 and the Nasdaq Composite indexes also hit record intraday highs.
The Dow came within a point of the historic mark on Jan 6, as investors banked on pro-growth policies and tax cuts many expect from the new administration.
“Trump’s been on the job for five days and he’s a man of action,” said Brian Battle, director of trading at Performance Trust Capital Partners in Chicago.
“That should get everyone confident he’ll get those three other things done ... which is taxes, trade and regulation.”
Trump tweeted “Great!-Dow20K”.
The venerable index had stalled recently, dropping modestly in consecutive weeks, as investors grew cautious as they looked for clarity on the administration’s new policies.
If the index remains above 20,000 by closing time, the 42-session surge from the first close above 19,000 would mark the second-shortest length of time between such milestones.
The most rapid rise was between 10,00 and 11,000 from March 29 to May 3, which took 24 days. The rise from 18,000 to 19,000 took the Dow 483 trading sessions.
The surge since Nov 22, when the index closed above 19,000 for the first time, has been spearheaded by financial stocks - with Goldman Sachs and JPMorgan accounting for about 20 percent of the gain.
On Wednesday, Boeing rose 2.7% after its earnings and IBM gained 1.4%, helping to push the index over the top. Goldman rose 0.7%.
At 10:11am ET (1512 GMT), the Dow was up 137.14 points, or 0.69%, at 20,049.85. Only six of its 30 components were lower.
The S&P 500 was up 13.69 points, or 0.60%, at 2,293.76 and the Nasdaq Composite was up 40.53 points, or 0.72%, at 5,641.49.
Eight of the 11 major S&P 500 sectors were higher, led by a 1.05% rise in financials.
Utilities, real estate and telecom services - defensive parts of the market - were the outliers.
Advancing issues outnumbered decliners on the NYSE by 1,941 to 824. On the Nasdaq, 1,902 issues rose and 658 fell.
The S&P 500 index showed 71 new 52-week highs and one new low, while the Nasdaq recorded 145 new highs and six new lows. - Reuters