The 1,000-point moves become less impressive on a percentage basis, however.
The Dow climbed 10 percent in 1999, while it's risen only 5 percent in the move from 20,000 to 21,000.
The "biggest takeaway may be psychological — round numbers make for good headlines/celebrations, and this could prompt the sort of blow-off that leaves stocks (at least in the near-term) over-extended and facing headwinds from excessive optimism," William Delwiche, investment strategist at Baird, said in an email.
U.S. stocks rallied to fresh records Wednesday after a speech from Donald Trump took a less confrontational tone, although the president gave few details on highly anticipated policies such as tax reform.
Goldman Sachs contributed the most to gains in the Dow on Wednesday and has had the biggest positive effect on the index's gains since it crossed 19,000 two weeks after the election, according to Howard Silverblatt, senior index analyst at S&P Dow Jones Indices.
However, since the Dow topped 20,000 in late January, Apple has had the greatest positive impact, he said.