On the 1st of March she was ordered from the Bremerton Yard, in the State of Washington, to San Francisco, and thence to report in the Atlantic.

Her voyage was the longest emergency run undertaken up to that time by a modern battleship.

The outbreak of the war with Spain meant the sealing of all ports in which she might have been repaired in case of emergency.
Rumors were rife of Spanish vessels ready to intercept her, and the eyes not only of the United States but of the world were upon the Oregon.
A feeling of relief and rejoicing therefore passed through the country when this American warship arrived at Key West on the 26th of May, fit for immediate and efficient service.
The fleet, though concentrated in the Atlantic within the region of immediate hostility, was divided for purposes of operation into a major division under the immediate command of Admiral Sampson and a flying squadron under Commodore Schley.

* The first undertook the enforcement of the blockade which was declared on the 21st of April against Cuba, and patrolled the northern coast from Gardenas to Bahia.

Key West was soon filled with Spanish prizes.