The move higher was not a straight line. Stocks lost some momentum in the last several weeks while the market consolidated gains.
"We do think bigger picture, this bull market, out into next year should continue," said Ryan Detrick, senior market strategist at LPL Financial. "It took a little bit longer than I expected to get to 20,000, and the recent consolidation was nice to work off the overbought conditions coming into this year."
Detrick said while 20,000 is getting the attention, the action under the surface is encouraging and in some ways more important. He said the rally in small caps Tuesday and Wednesday signals that they may regain leadership which would be a plus for the overall market.
Detrick said the previous record for a 1,000-point gain was 24 days from the time the Dow first crossed 10,000 to 11,000, in 1999.
"Normally it takes 24 months to go from each thousand-point level. We did it in two months," said Sam Stovall, chief investment strategist at CFRA.
The Dow has closed at record highs 17 times since Election Day. It came within 0.037 point — 19,999.63 — during the Jan. 6 trading day.
The first trip to to a five-digit number was a big event for the stock market, when the Dow reached 10,000 in 1999, the height of the tech bubble. But it was a failed start, and the Dow crashed back to the 6,547 in the depths of the financial crisis in March 2009 before returning to 10,000 later that year.
"It took 17 years. That's a long time to double in value," said Wharton finance professor Jeremy Siegel. "We were at the top of the biggest bubble at the end of 1999 that we've ever been in. This is nowhere like the bubble we had before. I think the market is much more reasonably valued than when we hit 10,000."
Siegel expects the market to keep moving higher on the back of promises from President Donald Trump to cut taxes and regulations, but it will have to see action to keep moving. "I don't think we're going to get to 21,000 as fast as we went from 19,000 to 20,000. It's going to take a quarter," said Siegel.
Trump has suggested tariffs for companies that move out of the U.S. and has said he wants to change trade deals. Those things concerned investors during the election, and traders are eyeing his moves on trade. "That is a risk out there. Probably if we knew for sure he wasn't going that way, the market would be even higher than it is," said Siegel.
Analysts say the market could consolidate after it hits 20,000 and while it waits to see more signs that the economy is stronger and will support improving earnings. Reaching 21,000 too quickly would be a negative.
"I would really get scared if that were the case. We're already in the beginning of a 'FOMO' environment — fear of missing out," said Stovall.
Stovall said on average, the market rose another 4 percent over the next 2½ months after the Dow reached a new 1,000-point milestone. Then it would decline by 5 percent or more. There were two times when it did not digest gains before reaching the next 1,000 threshold. Once was the move to 11,000 in 1999, and then again in 2007.
"The longer we go, it's more borrowed time," said Stovall. "I would say that we would experience a pullback, or a correction but definitely not a correction."
Stovall points out the bull market is set to enter its eighth year on March 9.
"Bull markets go out with a bang, not a whimper. It makes me feel confident that we're not coming to the end of a bull market," he said.
Detrick said he expects to see Dow 21,000 in 2017. "You don't want it to make 21,000 too fast. That could be some sort of blow off equity top."
Stovall said big numbers don't really mean much but they can excite investors. "It's like a gigantic magnet that pulls investors towards it, and sort of becomes a self-fulfilling prophecy. The question is what happens once we eclipse it?"
He said the millennium levels are like rusty doors, requiring several pushes before they break open.
"Usually that honeymoon period lasts for 100 days, and interesting that the honeymoon ends in April, the traditional sell-in-May period," he said.
It's a positive that financial stocks are leading the Dow's gains, but it's because there are expectations of higher rates and that some banking regulations will be lifted.
"The financials is much more of a Trump situation because of the expected lifting of regulatory pressures, combined with the Fed's effort which would steepen the yield curve and improve their net interest income prospects," said Stovall.
Stovall said the financials are an early-cycle mover. "They're sort of like the Dow Transports, from a Dow theory perspective. They have to confirm upward moves," he said.
Since just before the election on Nov. 1, the financial sector was up 18 percent, followed by materials, up 12.5 percent and industrials, up 11 percent. Consumer discretionary is up 8.6 percent.
Those sectors could continue to gain. "Since 1990, the cyclical sectors, materials and discretionary and tech have traditionally outperformed the S&P 77 percent of the time in the November through April period," he said.