Bonanza is located at the east end of Oregon Route 70, the shortest state highway in Oregon, and is approximately 25 miles from Klamath Falls.

According to the United States Census Bureau, the city has a total area of 0.8 square miles (2.1 km²), all of it land.

As of the census of 2000, there were 415 people, 139 households, and 102 families residing in the city. The population density was 497.8 people per square mile (193.1/km²). There were 152 housing units at an average density of 182.3/sq mi (70.7/km²).

The racial makeup of the city was:85.54% White0.48% African American0.96% Native American0.24% Asian0.72% Pacific Islander5.54% from other races6.51% from two or more races13.01% of the population were Hispanic or Latino of any race

There were 139 households out of which:37.4% had children under the age of 18 living with them59.0% were married couples living together13.7% had a female householder with no husband present25.9% were non-families22.3% of all households were made up of individuals9.4% had someone living alone who was 65 years of age or older

The average household size was 2.99 and the average family size was 3.40.

The age distribution was:34.9% under the age of 187.7% from 18 to 2425.1% from 25 to 4420.5% from 45 to 6411.8% who were 65 years of age or older

The median age was 31 years. For every 100 females there were 99.5 males. For every 100 females age 18 and over, there were 92.9 males.

The median income for a household in the city was $31,944, and the median income for a family was $36,786. Males had a median income of $21,979 versus $18,750 for females. The per capita income for the city was $10,213. About 14.7% of families and 16.8% of the population were below the poverty line, including 21.9% of those under age 18 and 11.9% of those age 65 or over.

Coordinates: 42°11′58″N 121°24′17″W / 42.199333°N 121.404639°W / 42.199333; -121.404639