According to the United States Census Bureau, the town has a total area of 10.6 square miles (27.5 km²), of which, 10.5 square miles (27.3 km²) of it is land and 0.1 square miles (0.2 km²) of it (0.57%) is water.
The town of Apex was incorporated in 1873, named for its location as the highest point on the Chatham Railroad between Richmond, Virginia and Jacksonville, Florida. Apex grew slowly through the succeeding decades, despite several devastating fires, including a 1912 conflagration which destroyed most of the downtown business district. The town center was rebuilt and stands to this day, now one of the most intact railroad towns in the state. At the heart of town stands the Apex Union Depot, originally passenger station for the Seaboard Air Line Railroad and later home to the locally-supported Apex Community Library. The depot now houses the Apex Chamber of Commerce.
Apex suffered mild setbacks during the Depression-era, but growth began again in earnest in the 1950s. The town's position in proximity to North Carolina's Research Triangle Park spurred additional residential development, yet the town managed to preserve its small-town character. During the 1990s, the town's population quadrupled to over 20,000, placing new demands upon Apex's infrastructure.
Apex has continued to grow in recent years. A sizable shopping center was built at the intersection of Highway 55 and US 64, and several new neighborhoods have been built as the town grows toward the west. Several "infill" projects are also underway.
In October 2006, a chemical fire in an Apex waste processing facility generated worldwide headlines when much of the town was temporarily evacuated. There were few serious injuries, and residents were soon able to return home.
In July 2007, CNN/Money magazine ranked Apex #14th on its list of the nation's top 100 small towns.
Keith Weatherly is the mayor of Apex and was first elected to the post in 1995 after serving for 2 years on the town council. He is currently serving his 3rd term. The Mayor pro tem is Mike Jones (4th term). Councilmen include Bryan Gossage (2nd term), Bill Jensen (3rd term), Gene Schulze (2nd term) and Bill Sutton (1st term). The current Town Manager is Bruce Radford.
There were 7,397 households out of which 46.1% had children under the age of 18 living with them, 66.2% were married couples living together, 7.2% had a female householder with no husband present, and 24.5% were non-families. 18.5% of all households were made up of individuals and 2.6% had someone living alone who was 65 years of age or older. The average household size was 2.73 and the average family size was 3.16.
In the town the population was spread out with 30.8% under the age of 18, 5.4% from 18 to 24, 44.8% from 25 to 44, 15.0% from 45 to 64, and 4.0% who were 65 years of age or older. The median age was 31 years. For every 100 females there were 97.8 males. For every 100 females age 18 and over, there were 94.0 males.
The median income for a household in the town was $71,052, and the median income for a family was $78,689. Males had a median income of $55,587 versus $37,057 for females. The per capita income for the town was $28,727. About 1.2% of families and 1.9% of the population were below the poverty line, including 1.2% of those under age 18 and 7.8% of those age 65 or over.