The 21st Arizona Territorial Legislative Assembly was a session of the Arizona Territorial Legislature which convened in Phoenix, Arizona. The session ran from January 21, 1901, till March 21, 1901. It was the first session of the territorial legislature to meet in the territorial capital building and overrode more vetos than any other session.
The previous session of the legislature had authorized creation of a committee "to revise the laws and eliminate therefrom all crude, improper and contradictory matter and also to insert such new provisions as they may deem necessary and proper." The revised code proposed by the committee was based upon the civil code of Texas and the criminal code of California as was ready as the 21st session began.
In an effort to speed the statehood process, the 16th Arizona Territorial Legislature had authorized a constitutional convention for Arizona. The resulting 1891 document had not however resulted in statehood for the territory. Opposition coming first from Republicans who did not wish to see two new U.S. Senators from the predominantly Democratic territory and later from Gold Democrats who opposed the proposed constitution's support for free silver.
Construction of the territorial capital building was completed in early 1901. Dedication of the building occurred on February 24, 1901, 38 years after passage of the Arizona Organic Act. The US$130,000 previously authorized for construction of a territorial capital building had proved insufficient with $5,744.29 in unfunded costs left unpaid.