Sample of Sonoma Communities
The following are some of the communities located in Sonoma County:
| Community | 2009
Population | 2000
Population | Change
(2009 vs. 2000) |
| Santa Rosa | 157,468 | 147,595 | 6.69% increase |
| Petaluma | 55,178 | 54,548 | 1.15% increase |
| Rohnert Park | 40,921 | 42,236 | 3.11% decrease |
| Windsor | 25,619 | 22,744 | 12.64% increase |
| Healdsburg | 11,143 | 10,722 | 3.93% increase |
| Sonoma | 10,008 | 9,128 | 9.64% increase |
| Cloverdale | 8,220 | 6,831 | 20.33% increase |
| Sebastopol | 7,600 | 7,774 | 2.24% decrease |
| Cotati | 7,234 | 6,471 | 11.79% increase |
Counties Neighboring Sonoma
The following counties adjoin and form the boundaries of Sonoma:
| County | Direction | 2009
Population | 2000
Population | Change
(2009 vs. 2000) |
| Contra Costa |  SE | 1,041,274 | 948,816 | 9.74% |
| Lake |  N | 65,279 | 58,309 | 11.95% |
| Marin |  S | 250,750 | 247,289 | 1.4% |
| Mendocino |  NW | 86,040 | 86,265 | -0.26% |
| Napa |  E | 134,650 | 124,279 | 8.34% |
| Solano | E | 407,234 | 394,542 | 3.22% |
The western boundary of the county is on the Pacific Ocean and the southeastern boundary is on San Francisco Bay.
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