Once famous for producing navel oranges and starter homes, Riverside, Calif. is the latest suburb to fall inside the restlessly expanding boundaries of Los Angeles' regional office market.

Office construction in the Inland Empire — the brand name for Riverside and San Bernardino counties — has nearly doubled in the past year. Some 830,000 sq. ft. of office space was completed in the third quarter, with another 2 million sq. ft. still under construction. The bulk of that development is in Riverside, where construction cranes hover above 1.6 million sq. ft.

If a single project symbolizes the mushrooming commercial growth in Riverside, it is Turner RiverWalk, a master-planned, mixed-use business park being built by locally based Turner Development Corp. of Orange County.

The $200 million project, the final phase of which is slated for completion in May, is a cornucopia of mixed-use: 400,000 sq. ft. of industrial and distribution space, 500,000 sq. ft. of office space, including a pair of medical office buildings; and 100,000 sq. ft. of retail. Add to the mix a 119-suite business hotel. Plunked down amid 1,100 newly finished single-family homes, Turner RiverWalk supplies a full array of commercial uses within a single development.

Turner Development has inserted this enormous project into a residential neighborhood as neatly as a computer technician would snap a motherboard into a desktop. RiverWalk has “created an office market in West Riverside, where there wasn't one before,” says Tricia Hinckley, the city's economic development manager.

She credits the developers with being “smart and strategic,” for starting the project with industrial buildings, then progressing to smaller two-story office buildings, then finally to taller office buildings and a hotel.

Location is one obvious reason for Riverside's rising fortunes. The city is situated only 15 miles east of Orange County, the office-rich region that is home to many employers of the Riverside labor force.

Affordably priced housing is dramatically boosting the size of the population in the region by 100,000 people annually, according to the Inland Empire Economic Partnership, a non-profit research group. The current population of the Inland Empire is estimated at 3.4 million.

Riverside finds itself repeating the classic growth pattern of Southern California. Affordable housing attracts young, well-educated workers. When this labor pool reaches a critical mass, it attracts new office buildings and retail.

The highly varied range of building types in RiverWalk is by design, according to Mike Kendall, vice president at Turner Development. Office tenants like to work near retail, he says, because they can drop off their dry cleaning and eat at nearby restaurants.

Similarly, retailers favor locations close to both residential neighborhoods and commercial complexes because homeowners shop in the evening, while office tenants provide lunchtime business.

With large parcels of available land increasingly scarce in Southern California, this 73-acre site is a rarity. It enables the developer to assemble different types of commercial tenants that are compatible.

“People who develop office buildings are usually stuck with what's been built around you,” says Kendall of Turner Development. At RiverWalk, in contrast, “we can control and plan a group of uses that co-exist peacefully.”