Every other US state settles for one design per flag. Oregon's has a front and a back that do not match: the state seal's shield in gold on navy blue on one side, a solitary gold beaver on the other. It is the only two-sided state flag left in the country, a survivor of a nineteenth-century style that every other state abandoned as too expensive to sew. Oregon adopted it in 1925, later than almost everyone else, and has since declined every invitation to simplify it.
A flag ordered by the post office
Oregon spent its first sixty-six years of statehood without an official flag, and the omission only became a problem through bureaucratic embarrassment. In the mid-1920s, Portland's postmaster, J. M. Jones, requested a state flag to forward to Washington, D.C., where the Post Office Department was assembling a display of all the states' flags. Oregon had nothing to send.
The legislature moved quickly by legislative standards. Senate Bill 195, "An Act Adopting a State Flag," passed and was signed by Governor Walter M. Pierce on February 26, 1925. The design leaned on precedent: Oregon's nineteenth-century military regiments had carried blue flags bearing the state seal's escutcheon, and the new civil flag kept that arrangement on its front while adding a beaver to the back. The first flag was sewn at the Meier & Frank department store in Portland, where seamstresses Blanche Cox and Marjorie Kennedy finished it in time for an all-states display at the 150th anniversary of the Battle of Lexington that April.
The obverse: a seal in gold
The front of the flag, prescribed in Oregon Revised Statutes 186.010, is the escutcheon from the state seal rendered entirely in gold on a navy field. The shield is a compressed history lesson. Mountains and forests, an elk with branching antlers, and a covered wagon recall the Oregon Trail migration. On the water behind them, a British man-of-war departs while an American merchant ship arrives, a pointed comment on the end of joint British-American occupation of the region. A ribbon across the shield reads The Union, a declaration of loyalty from a state admitted on the eve of the Civil War. Below it sit a sheaf of wheat, a plow, and a pickax for the state's farming and mining. An eagle perches on top.
Thirty-three stars ring the whole composition, one for each state in the Union when Oregon joined on February 14, 1859. STATE OF OREGON arcs above in gold block letters; 1859 sits below. The statute's specified proportions are an oddly precise 500:833, though flags sold in practice usually come in 3:5 or 2:3.
The reverse: the beaver
The back of the flag drops all of it, the shield, the stars, the lettering, for one animal. A gold beaver crouches on the navy field, drawn in profile. The choice needs little explanation in Oregon. The animal drove the fur trade that first brought sustained European and American commerce to the Pacific Northwest, pelts functioned as currency there for decades, and the state has been the Beaver State for as long as anyone has bothered with nicknames. The beaver is the official state animal, and it also fronts the athletic identity of Oregon State University.
There is something appealingly unbalanced about the arrangement: a flag that is dense civic heraldry from one angle and a single quiet animal from the other, depending on which way the wind holds it. In practice the beaver is the side most people never see. On a pole the flag is usually viewed from whichever side the observer happens to stand, and photographs, textbooks, and websites almost always reproduce the obverse. Oregon effectively maintains a second, semi-secret flag that only reveals itself to people who walk around the flagpole.
The last two-sided flag
Double-sided flags were not always rare. Nineteenth-century regimental colors often differed front and back, and several states carried the habit into their civil flags. Economics killed the practice. A two-sided flag is effectively two flags sewn back to back, sometimes with an opaque interlining between them so the designs do not show through each other; it costs roughly double, weighs more, and flies worse. One by one the states simplified. When Massachusetts eliminated the pine-tree reverse of its flag in 1971, Oregon was left as the only US state whose flag has a different design on each side. Among national flags, only Paraguay still does the same.
That distinction is now the flag's chief defense. Judged by the usual design standards it fares poorly: lettering, a date, a busy seal, all things the North American Vexillological Association's guidelines advise against. Redesign contests and proposals came in 1976, 2008, and 2013, and each time Oregonians preferred the flag they had. A state that famously prizes its own eccentricity is unlikely to trade the country's last two-sided flag for something cleaner, and so far it hasn't.
References
[1] "Flag of Oregon," Wikipedia. https://en.wikipedia.org/wiki/Flag_of_Oregon
[2] "Oregon State Flag," The Oregon Encyclopedia, Oregon Historical Society. https://www.oregonencyclopedia.org/articles/oregon_state_flag/
[3] Oregon Revised Statutes § 186.010, description of the state flag.
[4] "Flag of Oregon," Encyclopaedia Britannica. https://www.britannica.com/topic/flag-of-Oregon
[5] "What Is the Only Two-Sided State Flag?," WorldAtlas. https://www.worldatlas.com/articles/what-is-the-only-two-sided-state-flag.html