City in King County, Washington · 4.4 sq mi · 2,949 people per sq mi
13,079 people live in Newcastle. The typical household earns $160,278, and the median resident is 37.5 years old.
2026 projection
From 13,017 in 2020
Poverty rate 5.93%
Men 36.6 · Women 38.7
1980–2026
13,079
2026 projection
0.5% since 2020 (increase)
Source: U.S. Census Bureau decennial counts and annual estimates, including 2010–2020 intercensal estimates. 2026 is a projection. Values between recorded years are interpolated.
Use the left and right arrow keys to inspect population observations.
1980–2026
13,079
2026 projection
0.5% since 2020 (increase)
Source: U.S. Census Bureau decennial counts and annual estimates, including 2010–2020 intercensal estimates. 2026 is a projection. Values between recorded years are interpolated.
Use the left and right arrow keys to inspect population observations.
| 2026 | 13,079 | -49 | 0.37% |
|---|---|---|---|
| 2025 | 13,128 | +170 | 1.31% |
| 2024 | 12,958 | +151 | 1.18% |
| 2023 | 12,807 | -56 | 0.44% |
| 2022 | 12,863 | -117 | 0.90% |
| 2021 | 12,980 | -37 | 0.28% |
| 2020 | 13,017 | +504 | 4.03% |
| 2019 | 12,513 | +521 | 4.34% |
| 2018 | 11,992 | +51 | 0.43% |
| 2017 | 11,941 | +188 | 1.60% |
Showing 10 of 20 years.
The 2020 row compares the April 1 Census count with the July 1, 2019 estimate (about nine months). Its Growth and Annual change therefore do not represent a full year.
Newcastle has a population change lower than King County, Washington, and the U.S.
Change from July 1, 2020 to July 1, 2025 population estimates—not annualized growth or site projections.
Source: U.S. Census Bureau. U.S. totals are summed from the 50 states and D.C.; unavailable comparisons are omitted.
U.S. Census Bureau, 2024 ACS 5-year estimates · Table S0101
Each square is about 1% of residents (roughly 130 people).
Hispanic or Latino residents can be of any race. All other groups exclude Hispanic residents.
U.S. Census Bureau, 2024 ACS 5-year estimates · Table B03002
Half of households earn more, half earn less
Typical yearly pay for a worker 25 or older.
About 1 in 17 residents
58% of residents age 15 and older are married.
| Status | Overall | Male | Female |
|---|---|---|---|
| Married | 58% | 63% | 55% |
| Never married | 28% | 29% | 27% |
| Divorced | 8% | 8% | 8% |
| Widowed | 5% | 0% | 10% |
| Separated | <1% | 0% | <1% |
U.S. Census Bureau, 2024 ACS 5-year estimates · Table S1201
14 sources