San Diego County

Key demographics – San Diego County, California

Population size

• Total population: 3,298,634 (2020 Census)
• Latest estimate: approximately 3.28–3.30 million (U.S. Census Bureau/ACS recent vintages)

Age

• Median age: about 36–37 years
• Age distribution (approximate):
  • Under 18: ~22%
  • 18–64: ~63–64%
  • 65 and over: ~14–15%

Gender

• Male: ~50–51%
• Female: ~49–50%

Racial/ethnic composition (shares of total population)

• Hispanic or Latino (any race): ~34–35%
• Non-Hispanic White: ~43–45%
• Non-Hispanic Asian: ~13%
• Non-Hispanic Black or African American: ~5%
• Non-Hispanic Two or more races: ~3–4%
• Non-Hispanic American Indian/Alaska Native: ~1%
• Non-Hispanic Native Hawaiian/Other Pacific Islander: ~0.5–0.7%

Households and housing

• Total households: about 1.13–1.15 million
• Average household size: ~2.8–2.9 persons
• Family households: ~64–66% of households
• Tenure: ~54–55% owner-occupied; ~45–46% renter-occupied

Notes

• Figures reflect U.S. Census Bureau data (2020 Decennial Census; latest American Community Survey estimates). Rounding causes components to not always sum to 100%.

• Population baseline: ≈3.30 million residents (U.S. Census Bureau, 2023).
• Estimated email users: ≈2.36 million adults (18+) use email, applying Pew Research’s ≈92% email adoption among U.S. adults to San Diego County’s ≈2.57 million adults.
• Age distribution of adult email users: roughly mirrors the adult population mix due to near‑universal adoption—≈32% ages 18–34, ≈50% ages 35–64, ≈18% ages 65+.
• Gender split: effectively even (≈50/50); national studies show no material gender gap in email adoption.
• Digital access and devices (ACS 2018–2022, San Diego County):
  • Households with a computer: ≈96%.
  • Households with a broadband internet subscription: ≈93%.
  • Implication: about 7% of households lack home internet and are more likely to rely on mobile data or public Wi‑Fi for email.
• Trends and density/connectivity facts:
  • Population density ≈780–785 people per square mile (county land area ≈4,206 sq mi), with dense coastal/urban corridors (San Diego, Chula Vista, Oceanside) enjoying multiple cable/fiber options and higher speeds.
  • Rural East County and mountain/desert areas show lower subscription rates and more coverage variability, contributing to a modest urban–rural digital divide impacting email access frequency rather than basic adoption.

Sources: U.S. Census Bureau (ACS/QuickFacts, 2018–2022; 2023 pop. est.); Pew Research Center on adult email usage.

Mobile phone usage in San Diego County, CA (2024 snapshot)

User estimates

• Population and users: About 3.30 million residents and roughly 1.15 million households. An estimated 2.8–2.9 million unique mobile phone users (any mobile device), equal to about 86–88% of residents. Among adults, mobile phone ownership is effectively near-universal (>95%).
• Smartphone users: Approximately 2.55–2.65 million residents aged 13+ use smartphones. This combines national age-specific smartphone adoption with San Diego’s age mix.
• Active mobile connections: Approximately 3.3–3.7 million active cellular lines (including phones, tablets, wearables, and IoT), or roughly 100–115 lines per 100 residents, in line with or slightly above California’s overall density.

Demographic breakdown (what stands out locally)

• Age
  • 13–17: ~95% smartphone adoption; heavy messaging/social app use; strong dependence for school/community safety alerts.
  • 18–29 and 30–49: ~97–98% smartphone adoption; highest 5G usage and multi-line/device ownership. San Diego’s sizable student and military populations push data use per user slightly above the state average.
  • 50–64: ~88–92% smartphone adoption; high adoption of mobile banking, telehealth, and navigation.
  • 65+: ~70–80% smartphone adoption; adoption is rising but still lags younger cohorts. Voice-first/basic-phone users are concentrated here, especially in exurban East County.
• Income and access
  • Mobile-only internet: Lower than the statewide share. Smartphone-only (no home broadband) households are roughly 10–12% in San Diego County versus about 11–15% statewide, reflecting stronger cable/fiber availability in the urbanized coast and central neighborhoods.
  • Cost sensitivity: Subsidy and ACP-like successor program participation skews to South Bay and inland communities; device financing and MVNO plans are common among lower-income users.
• Race/ethnicity and cross-border behavior
  • Hispanic/Latino residents (roughly one-third of the county) show very high smartphone adoption and above-average use of WhatsApp and cross-border calling/roaming. Dual-SIM or dual-line usage (U.S. and Mexico) is more prevalent than the California average due to proximity to Tijuana.
• Military and students
  • One of the nation’s largest military communities and multiple large universities (e.g., UCSD, SDSU) contribute to higher unlimited-plan penetration, hotspot use, and early 5G adoption relative to the state overall.

Digital infrastructure and performance

• Coverage
  • 5G population coverage exceeds 95% in the urban/suburban coastal corridor (T-Mobile, Verizon, AT&T), with mid-band 5G as the primary layer. mmWave hotspots are deployed in dense areas and venues (e.g., downtown/Gaslamp, Petco Park, Snapdragon Stadium, UCSD/La Jolla).
  • Coverage gaps persist in eastern mountain/desert areas, canyons, and on/near some tribal lands; these gaps affect a smaller share of the population than in many other California counties but remain material for emergency communications and commuting corridors (I-8, SR-67, SR-78).
• Capacity and speeds
  • Urban San Diego typically sees higher 5G median downlink speeds than the statewide average due to extensive mid-band deployments (e.g., 2.5 GHz and C-band) and dense small-cell buildouts in coastal ZIP codes. Exurban East County speeds fall back to low-band 5G/LTE in places.
• Operators and spectrum
  • All national operators (AT&T, T-Mobile, Verizon) operate robust 5G networks; Dish’s 5G network is commercially live in the county. Mid-band spectrum (2.5 GHz, C-band, 3.45 GHz) underpins most daily performance; mmWave is venue/downtown-focused.
• Backhaul and fiber
  • Strong metro fiber from multiple providers supports dense small-cell and macro backhaul, with cable and growing FTTH footprints enabling rapid 5G site turn-up and more reliable emergency alerting. This backhaul depth is a comparative advantage versus many non-metro California areas.
• Fixed wireless access (FWA)
  • Rapid FWA uptake (T-Mobile, Verizon) in apartments and lower-fiber neighborhoods; still a smaller share of home internet than cable/fiber countywide, but growing faster than the state average in select inland ZIP codes.

How San Diego differs from California overall

• Higher urban 5G performance and earlier mid-band/mmWave densification, influenced by the local wireless R&D ecosystem and venue-focused builds.
• Lower smartphone-only household share than the state, thanks to strong cable/fiber availability and adoption in the coastal/central urban core.
• More dual-line and cross-border usage, reflecting proximity to Mexico and a large bilingual population.
• Higher unlimited-plan and hotspot usage tied to large student and military populations.
• Rural coverage issues exist but affect a smaller population share than in many California counties; however, canyon/mountain topography causes pronounced local dead zones that matter for wildfire and evacuation communications.

Key takeaways

• Mobile phone use is ubiquitous in San Diego County, with roughly 2.8–2.9 million unique users and 2.55–2.65 million smartphone users 13+.
• San Diego over-indexes on 5G capacity and user data consumption in the coastal urban belt and venues, while exurban East County and some tribal lands trail in coverage and throughput.
• Compared with the California average, San Diego combines better urban 5G performance and lower mobile-only dependence with distinct cross-border usage patterns and strong military/student-driven demand.

Sources for estimates and comparisons: U.S. Census Bureau (ACS 2023 population and age mix), Pew Research Center (2023 smartphone adoption by age), USC–CETF California Broadband Adoption studies (household access and smartphone-only shares), FCC/CPUC mobile coverage maps and carrier public network disclosures (2023–2024).

San Diego County social media snapshot (2024–2025)

Headline user stats

• Population: ≈3.3M residents; ≈2.8M are age 13+.
• Social media users (13+): ≈2.4M (≈85% penetration). Adults (18+) account for ≈2.16M of these users; teens (13–17) ≈0.18–0.20M.
• Device mix: >90% of users access primarily via smartphone; video is the dominant format across platforms.

Age breakdown of users (share of total users)

• 13–17: ≈8%
• 18–24: ≈13%
• 25–34: ≈21%
• 35–44: ≈19%
• 45–54: ≈15%
• 55–64: ≈14%
• 65+: ≈11%

Gender breakdown of users

• Female ≈51%
• Male ≈49% Notes: Women over-index on Facebook, Instagram, and Pinterest; men over-index on Reddit, X, and YouTube. Overall split is close to even.

Most-used platforms among adults in San Diego County (aligning with large urban US usage; local uplift noted where relevant)

• YouTube: ≈80–85% of adults
• Facebook: ≈65–70%
• Instagram: ≈48–55%
• TikTok: ≈30–35%
• Snapchat: ≈25–30% (higher among 13–24)
• LinkedIn: ≈30–35% (slightly above US average given biotech/defense sectors)
• Pinterest: ≈30–35% (female skew)
• WhatsApp: ≈25–30% (above US average due to cross‑border and bilingual communities)
• X (Twitter): ≈20–25%
• Reddit: ≈20–25%
• Nextdoor: ≈15–20% (strong in suburban/homeowner areas)

Behavioral trends to note

• Mobile-first, video-forward: Short-form video (Reels, TikTok, Shorts) and Stories drive the highest reach; how‑to, outdoors, dining, and event content perform best.
• Bilingual and cross-border communication: High utilization of Spanish/English content; above-average adoption of WhatsApp and Facebook Groups for family, business, and Tijuana cross‑border coordination.
• Community and local discovery: Heavy use of Facebook Groups and Nextdoor for neighborhoods, schools, and military family networks; Instagram and TikTok for restaurant openings, hikes, beaches, and weekend plans.
• Event-driven spikes: Significant social chatter around Padres games, Comic‑Con, festivals, and surf/weather events; hashtags and geotags amplify local reach.
• Time-of-day patterns (Pacific Time): Engagement peaks on weekdays at lunch (11am–1pm) and evenings (7–10pm); weekends show strong mid‑morning to afternoon activity.
• Youth behaviors: Teens/young adults favor Snapchat and TikTok for messaging and discovery; ephemeral content and creator-led recommendations influence dining, apparel, and entertainment choices.
• Professional networking: LinkedIn engagement is strong midweek work hours, reflecting biotech, defense, higher ed, and tourism sectors; thought-leadership and hiring content perform well.
• Reviews and UGC: Decisions about restaurants, coffee, fitness, and outdoor gear are heavily influenced by Instagram/TikTok UGC and local creator posts rather than traditional ads.

Sources and methodology

• Estimates synthesize 2024–2025 Pew Research Center US platform usage benchmarks, 2023–2024 American Community Survey age/sex composition for San Diego County, and platform advertising planning tools. Local adjustments applied for bilingual/cross‑border dynamics and industry mix.