Like every district in Oregon, the lines for House District 31 are a little bit different this year. The district includes almost all of Columbia County (everything except Clatskanie and the area north and west of it), the northwest half (or so) of Washington County, the parts of Multnomah County including Sauvie Island and the land roughly west of it, and a tiny slice of Yahmill County just south of Gaston.

House District 31 and House District 32 make up Senate District 16.

You can also see a PDF of the official map from the Oregon Legislature, as well as an interactive map of all the new districts.