Oregon gets a lot of rain and animals that do well in lots of water often have webbed feet.
In addition, the University of Oregon has the duck as their mascot and ducks have webbed feet.
Portland is not a US state. It's a city in Oregon. Oregon's nicknames are the Sunset State, the Hard-Case state, the Web-Foot state, and the beaver state. As far as Portland goes, it's called the Rose City.
The web address of the Oregon State Mental Hospital Museum is: http://oshmuseum.org
The web address of the Thompson'S Mills State Heritage Site is: www.oregonstateparks.org
The web address of the Tryon Creek State Park is: http://www.oregonstateparks.org/park_144.p
The web address of the Museum Of Oregon Territory is: http://www.clackamashistory.org
The web address of the Oregon Jerusalem Historical is: www.ojhs.org
The web address of the Oregon Museums Association is: www.oregonmuseums.org
The web address of the Oregon Historical Society is: http://www.ohs.org
The web address of the Oregon Film Museum is: http://oregonfilmmuseum.com
The web address of the Oregon Maritime Museum is: http://www.oregonmaritimemuseum.org/
The web address of the Oregon Jewish Museum is: http://www.ojm.org
The web address of the Eastern Oregon Museum is: http://www.hainesoregon.com