City comparison
Castro Valley, CA is about 10 miles (10 km) from Union City, CA in a straight line. By road, the drive is roughly 10 miles, or about 10 min behind the wheel at highway speeds.
Driving distance is a rough estimate (great-circle × 1.25); driving time assumes a 60 mph blended average. Real trips run 10–20% longer with stops.
A direct flight from Castro Valley, CA to Union City, CA takes about 1 min, covering roughly 10 miles in a straight line. Connecting itineraries with a layover typically add 1–3 hours.
Block-to-block estimate at ~500 mph cruise, including taxi, climb, and descent — what an airline would publish, not pure airborne time.
Union City has a population of 69,502, vs 65,444 in Castro Valley — about the same size. By land area, Union City covers about 19 sq mi vs 17 sq mi for Castro Valley.
Population from US Census ACS. Land area from the Census Gazetteer (city proper, excluding inland water).
Cost indices by category, with the US city average (100) marked.
Index: 100 = US city average. Lower is more affordable.
Side-by-side costs, salaries, and sub-category indices.
| Metric | Castro Valley | Union City | Difference |
|---|---|---|---|
| Median rent | $2,383/mo | $2,593/mo | 8.8% higher in Union City |
| Median home value | $1,013,900 | $1,006,600 | 0.7% higher in Castro Valley |
| Median household income | $132,174 | $138,013 | 4.4% higher in Union City |
| Groceries index | 108.1 | 108.1 | ≈ equal |
| Utilities index | 168.3 | 168.3 | ≈ equal |
| Transportation index | 106.1 | 106.1 | ≈ equal |
| Healthcare index | 106.0 | 106.0 | ≈ equal |
How much you'd need to earn in the other city to keep the same standard of living.
If you earn $100,000 in Castro Valley, you'd need $100,422 in Union City to maintain your standard of living.
Climate, safety, and demographics side by side.
Castro Valley, CA is about 0.4% cheaper overall than Union City, CA, based on our cost-of-living index. If you earn $80,000 in Castro Valley, you'd need about $80,338 in Union City to keep the same standard of living.