Orange County, California - Geography

Geography

According to the 2000 census, the county has a total area of 947.98 square miles (2,455.3 km2), of which 789.40 square miles (2,044.5 km2) (or 83.27%) is land and 158.57 square miles (410.7 km2) (or 16.73%) is water. It the smallest county in Southern California. The average annual temperature is about 68 °F (20 °C).

Orange County is bordered on the southwest by the Pacific Ocean, on the north by Los Angeles County, on the northeast by San Bernardino County and Riverside County, and on the southeast by San Diego County.

The northwestern part of the county lies on the coastal plain of the Los Angeles Basin, while the southeastern end rises into the foothills of the Santa Ana Mountains. Most of Orange County's population reside in one of two shallow coastal valleys that lie in the basin, the Santa Ana Valley and the Saddleback Valley. The Santa Ana Mountains lie within the eastern boundaries of the county and of the Cleveland National Forest. The high point is Santiago Peak (5,689 feet (1,734 m)), about 20 mi (32 km) east of Santa Ana. Santiago Peak and nearby Modjeska Peak, just 200 feet (60 m) shorter, form a ridge known as Saddleback, visible from almost everywhere in the county. The Peralta Hills extend westward from the Santa Ana Mountains through the communities of Anaheim Hills, Orange, and ending in Olive. The Loma Ridge is another prominent feature, running parallel to the Santa Ana Mountains through the central part of the county, separated from the taller mountains to the east by Santiago Canyon.

The Santa Ana River is the county's principal watercourse, flowing through the middle of the county from northeast to southwest. Its major tributary to the south and east is Santiago Creek. Other watercourses within the county include Aliso Creek, San Juan Creek, and Horsethief Creek. In the North, the San Gabriel River also briefly crosses into Orange County and exits into the Pacific on the Los Angeles-Orange County line between the cities of Long Beach and Seal Beach. Laguna Beach is home to the county's only natural lakes, Laguna Lakes, which are formed by water rising up against an underground fault.

Further information: List of rivers of Orange County, California

Residents sometimes figuratively divide the county into "North Orange County" and "South County" (meaning Northwest and Southeast—following the county's natural diagonal orientation along the local coastline). This is more of a cultural and demographic distinction perpetuated by the popular television shows "The OC", "The Real Housewives of Orange County" and "Laguna Beach", between the older areas closer to Los Angeles, and the more affluent and recently developed areas to the South and East. A transition between older and newer development may be considered to exist roughly parallel to State Route 55 (aka the Costa Mesa Freeway). This transition is accentuated by large flanking tracts of sparsely developed area occupied until recent years by agriculture and military airfields.

While there is a natural topographical Northeast-to-Southwest transition from inland elevations to the lower coastal band, there is no formal geographical division between North and South County. Perpendicular to that gradient, the Santa Ana River roughly divides the county between northwestern and southeastern sectors (about 40% to 60% respectively, by area), but does not represent any apparent economic, political or cultural differences, nor does it significantly affect distribution of travel, housing, commerce, industry or agriculture from one side to the other.