Area code 904 covers the northeastern corner of Florida, including Jacksonville, St. Augustine, and surrounding counties like Duval, Clay, and Nassau. Introduced in 1965, 904 originally served a much larger area but has since been reduced due to splits creating area codes 352, 850, and others. Jacksonville, the largest city in Florida by land area and population, anchors the 904 region and serves as a center for banking, insurance, logistics, healthcare, and military operations. Major employers include CSX, Baptist Health, and Naval Station Mayport. The area benefits from a growing economy, relatively low cost of living, and a strategic location with access to major highways, railways, and deep-water ports. The city also boasts a vibrant arts and food scene, numerous beaches, and family-friendly suburbs. St. Augustine adds historical charm as the oldest continuously inhabited European-established settlement in the continental U.S. With ongoing growth and a balance of urban development and coastal lifestyle, 904 is a sought-after area for both residents and businesses. The area code is currently overlaid by 324, ensuring continued number availability while preserving 904’s local identity.