The Dow Jones industrial average crossed 23,000 mark for the first time on Tuesday — just two and a half months after it breached the 22,000 milestone.

Stocks boosting the blue-chip index included insurer UnitedHealth and Johnson & Johnson, which reported better-than-expected earnings.

Shares have mounted their historic rally amid continued optimism on Wall Street over President Trump’s plans to slash taxes and regulations, as well as continued strength in corporate profits. Still, some strategists wonder that the risks of a bubble are growing.

“A lot of this rise has been because of hopes of a tax cut, if there is any disappointment there, the answer to the bubble question is yes,” Peter Cardillo, chief market economist at First Standard Financial, told The Post.

Ironically, the optimism in the market could eventually signal a peak.

“There’s a lot of optimism, which means a lot of folks already have their money in the market. It’s a question of how much more will come in,” Bruce Bittles, chief investment strategist at Baird, told The Post.

But Bittles added that because the major indices are moving in tandem, the market is probably still strong — for now.

Bittles was not alone in noting that despite valid concerns, there are still positives in the market

“The fundamentals are good, which suggests no bubble,” Cardillo said pointing to good macroeconomic numbers as will as positive earnings this year, and walking back his tax-reform -related fears.

Other analysts — while optimistic about the market — offered some perspective on the latest crop of corporate earnings being released.

“Analysts knocked down their predictions because of the storms,” Jack Ablin, chief investment officer at BMO Private Bank, told The Post.

“It will be hard to gauge the general direction with all that has occurred last quarter,” Ablin added.

Even so, he couldn’t deny what he called a “remarkable rally” fueled by “slow, steady growth, corporate profits and low interest rates.”

If those persist, so will the rally, Ablin said.

And then there was talk of the significance — or, insignificance — of the Dow hitting another 1,000 point milestone.

“We’re hitting another psychological number and it brings out the question in people’s mind about how much higher it can go,” Jeff Carbone, Managing Director for Cornerstone Financial Partners told The Post.

The market “is not cheap anymore but we’re not at blowout numbers — it’s not at unprecedented territory,” Carbone added, noting that we may soon see 24,000.

But that wasn’t enough for one analyst.

“23,000 is not the number you watch, it’s 25,000,” Bittles said.