Lost River, Idaho Demographics & Population 2026

A note before these figures: with a population of 55, Lost River's ACS estimates come from a small number of survey responses and carry wide margins of error. Individual percentages below — particularly rates that round to 0% or 100% — are approximations, not precise measurements. See data.census.gov for the published margins of error.

Population Overview

Lost River is a small community located in Idaho, within Custer County. The total population is 55. It ranks as the 222nd most populous out of 232 Census-designated places in Idaho.

Age Demographics

The median age in Lost River is 76.9 years. This is 106% higher than the state median of 37.3 years. 58.2% of residents are 75 or older, suggesting a significant retirement-age population with implications for healthcare services and senior housing.

Economy, Income & Housing

The ACS records no residents below the poverty line in Lost River. In a community this small the estimate rests on very few survey responses, so it should be read as an absence of measurement rather than a measured absence of poverty. The survey records no unemployed residents in Lost River, which reflects the size of the sample rather than a labor market without joblessness. 100.0% of occupied housing units are owner-occupied. This homeownership rate is 39% higher than the state average of 72.1%.

Race & Ethnicity

The largest racial or ethnic group in Lost River is White (non-Hispanic), making up 76.4% of the population. Black or African American residents account for 10.9%. The Black or African American population is significantly higher than the state average (10.9% vs 0.7%). The Hispanic or Latino population (5.5%) is well below the state average of 13.7%. The Asian population is significantly higher than the state average (7.3% vs 1.3%).

Education

30.8% of residents aged 25 and older hold a bachelor's degree or higher. This is 3% lower than the state rate of 31.8%. Nationally, 35.7% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 94.2%. Notably, 30.8% of adults hold a graduate or professional degree, indicating a highly educated workforce.

Data Sources & Methodology

All demographic data for Lost River, Idaho is sourced from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates. The ACS collects data from approximately 3.5 million households annually and pools five years of responses so that even small communities can be measured, though the margin of error widens as the population falls. Comparisons are made against Idaho state averages and national averages calculated from the same dataset. Rankings reflect the city's position among all 232 Census-designated places in Idaho. Read more about how these figures are produced on our methodology page, or visit data.census.gov for official data.