It had been laying in the ground since 1917, but construction workers renovating an old building on the corner of 38th Street and Indian School unearthed the time capsule.
Project spokesperson Jaqueline Collier said the small tin box found under a cornerstone contained a yearbook and bylaws of the Madison Improvement Club, a group of women who promoted equality, arts, politics and philanthropy.
The box also contained newspapers, including one that read "Arizona, we will be a state," said Collier.
It appears the club was formed in 1910 and they raised funds to have a meeting place of their own.
The contents of the box are being preserved, and will be put on display in the building when the renovation is complete.
The building will soon become a wellness and fitness boutique.