The community is located on the south bank of the
Snake River across from
Weiser, Idaho; a bridge carrying
U.S. Route 95 Spur connects the two. It is north of
Ontario, the largest city in Malheur County, via
Oregon Route 201, which passes just south of Annex. According to the
U.S. Census Bureau, the Annex CDP has an area of , all land. ==Demographics==