FACTBOX: Oregon and its presidential primary

(Reuters) - Democrats Barack Obama and Hillary Clinton face off in Oregon on May 20 in the state-by-state process to determine who will take on Republican John McCain in the November presidential election.

Following are some facts about Oregon:

* Oregon conducts its elections by mail. Registered voters receive ballots two to three weeks before the election date, though they can also vote at an election office if they wish. Results will be available after 8 p.m. PDT.

* Obama is expected to win handily. One recent poll showed him leading Clinton by 12 percentage points.

* With a tradition of progressive, reform-minded government, Oregon has decriminalized medical marijuana, legalized assisted suicide and restricted land use to limit sprawl. But environmental restrictions are less popular in areas where the timber industry has been hamstrung by restrictions designed to protect the spotted owl.

* Politically, Oregon is split between liberal voters in large cities like Portland and conservatives in the rural east and south. Democrat Al Gore narrowly carried the state in the 2000 presidential election, while Democrat John Kerry defeated Republican President George W. Bush 51 percent to 47 percent in 2004.

* Oregon is the nation's top producer of Christmas trees. The state is also home to Nike shoes and a thriving high-tech industry.

SOURCES: Oregon Secretary of State, Almanac of American Politics, U.S. Census Bureau

(Compiled by Andy Sullivan)

(To read more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at blogs.reuters.com/trail08/ )