Sinai, South Dakota Demographics & Population 2026

A note before these figures: with a population of 215, Sinai'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

Sinai is a small community located in South Dakota, within Brookings County. The total population is 215. It ranks as the 227th most populous out of 439 Census-designated places in South Dakota.

Age Demographics

The median age in Sinai is 24.9 years. This is 34% lower than the state median of 38.0 years. With 43.7% of the population under 18, Sinai has a notably young demographic profile, suggesting a family-oriented community.

Economy, Income & Housing

The median household income in Sinai is $56,875. This is 24% lower than the state median of $75,081. It is also 30% lower than the national median of $80,734. The poverty rate stands at 1.9%. This is 84% lower than the state poverty rate of 11.9%. This exceptionally low poverty rate indicates strong economic prosperity across the community. The unemployment rate is 6.7%. This is 128% higher than the state rate of 2.9%. The median home value is $89,300. Housing costs are 65% lower than the state median of $257,400. With a home-value-to-income ratio of just 1.6x, Sinai is one of the most affordable housing markets in the area. 66.7% of occupied housing units are owner-occupied. This homeownership rate is 3% lower than the state average of 68.6%.

Race & Ethnicity

Sinai has a predominantly White (non-Hispanic) population, comprising 88.4% of all residents. Hispanic or Latino residents account for 11.6%. The Hispanic or Latino population is significantly higher than the state average (11.6% vs 4.8%).

Education

22.6% of residents aged 25 and older hold a bachelor's degree or higher. This is 29% lower than the state rate of 31.9%. Nationally, 35.7% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 77.4%.

Data Sources & Methodology

All demographic data for Sinai, South Dakota 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 South Dakota state averages and national averages calculated from the same dataset. Rankings reflect the city's position among all 439 Census-designated places in South Dakota. Read more about how these figures are produced on our methodology page, or visit data.census.gov for official data.