We won't forget about Alexander Hamilton: Jack Lew

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Alexander Hamilton will continue to be honored in some fashion on the $10 bill in addition to a yet-to-be announced woman, Treasury Secretary Jack Lew said Monday.

"It's been more than 100 years since we've had a woman on our currency. That's way overdue," he told CNBC's "Squawk Box" in a wide-ranging interview on topics that also included the need to raise the debt limit and get wages to move higher.

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Lew refused to say which woman will grace the new $10 bill or how Hamilton, the nation's first treasury secretary, would be honored.

However, he provided a possible hint. "If you look at the bill and turn it over, there's more than 1-square-inch of a bill to work with to make changes."

When pressed for more details, he said: "[There] are a number of things I can guarantee: We will honor Alexander Hamilton, a woman will be on our currency, and we're going to have some exciting news."

Lew said he plans to announce the changes by the end of the year, with completion of the redesign expected by 2020, the 100th anniversary of the passage of the 19th Amendment, giving women the right to vote.

Questions have been raised about why the $10 bill was chosen for the historic redesign.

Lew said it's all about security. "We want to make sure that our money is safe and sound; that it can't be counterfeited. ... The next bill that has to go through those kinds of improvements is the $10 bill," he continued.

The last bill to get an overhaul was the $100 in 2013. The likeness of Benjamin Franklin, one of America's founding fathers, remained on the front. But the bill got anti-counterfeiting features including a 3-D security ribbon.

Besides security updates, the new $10 bill is expected to include a tactile feature to assist the blind and visually impaired.

— AP contributed to this report.

Clarification: This version was clarified to reflect that the Treasury Department has said a woman will be "featured" on the $10 bill. The department has not specified whether the image will be on the front or back.