Greenhorn is a nearly non-populated city in Baker and Grant counties in the U.S. state of Oregon.

[9] It continued as a viable community until 1942 when gold mining was made illegal by Federal Public Law 208 during World War II.

In later years, the old Greenhorn Jail (dating to around 1910) was removed to Canyon City under suspicious circumstances.

The case was eventually heard by the Circuit Court for Grant County in Canyon City, Oregon.

[citation needed] According to the United States Census Bureau, the city has a total area of 0.1 square miles (0.26 km2), all land.