standard road signs have been altered to fit the left-side driving. Mail service is handled by the United States Postal Service, using the two-character state code "VI" for domestic mail delivery. ZIP codes are in the 008xx range. , specifically assigned codes include 00801–00805 (St Thomas), 00820–00824 (Christiansted), 00830–00831 (St. John), 00840–00841 (Frederiksted), and 00850–00851 (Kingshill). The islands are part of the North American Numbering Plan, using area code 340, and island residents and visitors are able to call most toll-free U.S. numbers. The U.S. Virgin Islands are located in the Atlantic Standard Time zone and do not participate in daylight saving time. When the mainland United States is on standard time, the U.S. Virgin Islands are one hour ahead of Eastern Standard Time. When the mainland United States is on daylight saving time, Eastern Daylight Time is the same as Atlantic Standard Time. Demographics In 2020, the census put the population of the U.S. Virgin Islands at 87,146, a decline of 18,989 (-18.1%) from 2010. In 2020, there were 39,642 households, out of which 24.1% had children under the age of 18 living with them, 27.8% were married couples living together, 20.5% had a female householder with no husband present, and 45.1% were non-families. 40.1% of all households were made up of individuals, and 16.4% had someone living alone who was 65 years of age or older. The average household size was 2.14 and the average family size was 2.98. In the territory, the population in 2020 was distributed with 19.6% under the age of 18, 8.0% from 18 to 24, 27.1% from 25 to 44, 24.9% from 45 to 64, and 8.4% who were 65 years of age or older. The median age was 33 years. For every 100 females, there were 91.4 males. For every 100 females ages 18 and up, there were 87.7 males. The annual population growth is −0.12%. The literacy rate for the adult population was 94.9% in 2010. Ethnic groups The racial makeup of the U.S. Virgin Islands as of the 2020 United States census: Black or Afro-Caribbean: 71.4% (64.2% Non-Hispanic Black) Hispanic or Latino of any race: 17.4% (8.9% Puerto Rican, 6.2% Dominican) White: 13.3% (12.7% Non-Hispanic Whites) Other: 6.3% Mixed: 7.4% Asian or Asian Caribbean: 1.0% Many residents can trace their ancestry to other Caribbean islands, especially Puerto Rico and the Lesser Antilles. The territory is largely Afro-Caribbean in origin. Languages