NATIONAL INTELLIGENCER, Washington, D.C., Sept. 12, 1850 

* California joins the Union (statehood)
* From the nation's capital

Not only does page 3 contain the official Act of Congress creating California as a state, the report is in the newspaper which was the unofficial voice of the government in any matters political.
Page 3 has: "An Act for the Admission of the State of California into the Union" noting that it was approved September 9.
Additionally, there are two other very notable Acts which were part of the historic Compromises of 1850: "An Act Proposing the State of Texas the establishment of her northern and western boundaries..." with a bit more, approved September 9. Also: "An Act to Establish a Territorial Government for Utah" also approved September 9.
Also, page 2 has a report from the House of Rep. noting the vote for the Fugitive Slave Bill, 107 yeas to 8 Nays. It would be enacted on September 18.
Four pages, very nice condition.