|• Total||3.8 sq mi (9.8 km2)|
|• Land||3.6 sq mi (9.3 km2)|
|• Water||0.2 sq mi (0.5 km2)|
|Elevation||69 ft (21 m)|
|• Density||2,108/sq mi (814.0/km2)|
|Time zone||UTC-5 (Eastern (EST))|
|• Summer (DST)||UTC-4 (EDT)|
|GNIS feature ID||0290820|
Seffner is a census-designated place (CDP) in Hillsborough County, Florida, United States. The population was 7,579 at the 2010 census, up from 5,467 at the 2000 census. ZIP codes for the Seffner area are 33584 and 33583.
Approximately 13 miles (21 km) east of downtown Tampa, Seffner serves as a suburban haven for commuters. While still characterized by towering live oak trees, strawberry farms and lakes, this small town has been growing rapidly. Housing subdivisions now dot the once rural landscape.
Seffner is located northeast of the center of Hillsborough County and is bordered by Thonotosassa to the north, Mango to the west, and Brandon to the south. Interstate 4 is the northern boundary of the CDP, and the southern boundary follows State Road 574 (Dr. Martin Luther King Jr. Boulevard). Plant City is 10 miles (16 km) to the east.
According to the United States Census Bureau, the Seffner CDP has a total area of 3.8 square miles (9.8 km2), of which 3.6 square miles (9.3 km2) are land and 0.2 square miles (0.5 km2), or 5.34%, are water.
As of the census of 2000, there were 5,467 people, 2,075 households, and 1,520 families residing in the community. The population density was 1,512.2 people per square mile (583.1/km²). There were 2,168 housing units at an average density of 599.7/sq mi (231.2/km²). The racial makeup of the community was 91.35% White, 3.26% African American, 0.29% Native American, 1.02% Asian, 2.71% from other races, and 1.37% from two or more races. Hispanic or Latino of any race were 8.21% of the population.
There were 2,075 households out of which 34.9% had children under the age of 18 living with them, 56.1% were married couples living together, 11.7% had a female householder with no husband present, and 26.7% were non-families. 21.5% of all households were made up of individuals and 8.9% had someone living alone who was 65 years of age or older. The average household size was 2.63 and the average family size was 3.04.
In the community the population was spread out with 26.4% under the age of 18, 7.7% from 18 to 24, 29.9% from 25 to 44, 24.4% from 45 to 64, and 11.6% who were 65 years of age or older. The median age was 37 years. For every 100 females, there were 95.4 males. For every 100 females age 18 and over, there were 90.0 males.
The median income for a household in the community was $42,614, and the median income for a family was $49,152. Males had a median income of $32,266 versus $26,328 for females. The per capita income for the community was $19,888. About 3.2% of families and 4.6% of the population were below the poverty line, including 4.0% of those under age 18 and 7.5% of those age 65 or over.
According to the Seffner Chamber of Commerce, the exact date of Seffner's founding is unknown. Some historians claim that Seffner's streets were originally laid out in 1862, but not recorded as a plat formally until 1885. Seffner's post office was opened in 1884, once a new railroad line in the area had been planned. The community was named for its first postmaster, F.P. Seffner. That same year, Seffner's first school and store were opened. The main thoroughfare leading north and south was Lenna Avenue, and leading east and west was Highway Number 23, renamed Buffalo Avenue, because of its erstwhile use as a buffalo trail, and then renamed again in 1989 to its current name, Dr. Martin Luther King, Jr. Boulevard (Hwy 574). Seffner (and neighboring Mango and Dover) served as the three primary towns along the South Florida Railroad right-of-way between Tampa and Plant City. These towns owe their existence and prosperity to the railroad, each becoming an important shipping center.
According to Ernest Robinson, County Historian, Seffner quickly became a prosperous small community with citrus groves, a hotel (later destroyed by fire), one drug store, several dry goods stores and a livery stable. Early pioneer families included Hooker, Weeks (after whom Lake Weeks was named), Simmons, Mitchell (the son became governor of Florida in the early 1900s), Pemberton, Franklin, Henderson, Wheeler, Tomberlin, Morris, Harvey, Derenthal, Little, O'Brien, Beaty, Baucom, Gray and Spencer.
When an epidemic of yellow fever hit Tampa in the fall of 1887 and in 1888, many Tampa refugees fled in panic to Seffner for temporary shelter in the hotel there (non-extant). However, as refugees and mail arrived in Seffner, they were fumigated as protection from the epidemic. Among the refugees was T.C. Taliaferro of the First National Bank of Tampa, who operated a branch banking business from Seffner during the epidemic.
The First Baptist Church of Seffner was founded in 1888.
The freeze in the winter of 1894–1895 brought disaster to Seffner. Many citizens left, while others remained to recoup their losses. Seffner survived and regained its affluence. Attractive residential neighborhoods were built to accommodate the influx of desirable residents. The beauty and popularity of the area, including Lakes Hooker, Locarno and Weeks, prompted others to relocate to the area. By 1925, Seffner was the fourth-largest town in Hillsborough County.
After World War II, Seffner became a sleepy Florida town with many residents relocating to Tampa. Today, visitors can still see vestiges of older buildings and farms along the back roads of Seffner. As Tampa and neighboring Brandon expand eastward, Seffner is expected to benefit from a boom in commerce and further residential development.
In early 2013 the town made headlines when one of its residents was swallowed up by a sinkhole that grew under his bedroom. Later in August 2015, the same sinkhole opened up again following heavy rains in the area.
- Matt Joyce, Oakland Athletics outfielder, raised in Seffner
- Andrew W.K., musician, lived in Seffner in 1999
- Rishi Nair, 2016 National Geographic Bee champion 
Hillsborough County Public Schools serves Seffner.
- Armwood High School
- Strawberry Crest High School
- Colson Elementary
- Seffner Elementary
- Lopez Elementary
- Hillsborough Baptist
- Legacy Christian Academy
- Seffner Christian Academy
Of some international renown is the Life Fellowship Bird Sanctuary, affiliated with a local church. Birds and reptiles are kept there, and the facility's success in breeding rock iguanas in captivity was reported in the press.
- "American FactFinder". United States Census Bureau. Retrieved 2008-01-31.
- "US Board on Geographic Names". United States Geological Survey. 2007-10-25. Retrieved 2008-01-31.
- "Geographic Identifiers: 2010 Demographic Profile Data (G001): Seffner CDP, Florida". American Factfinder. U.S. Census Bureau. Retrieved May 5, 2017.
- "Census of Population and Housing (1790-2000)". U.S. Census Bureau. Retrieved 2010-07-17.
- Hobson, Will, Laura C. Morel and Jodie Tillman. "Seffner Sinkhole 911 Call: 'Bedroom Floor Just Collapsed.'" Tampa Bay Times, March 1, 2013.
- Sinkhole that swallowed man in Seffner reopens. The Tampa Tribune. Retrieved August 19, 2015.
- Carpenter, Susan (March 24, 2002). "Pop Music: Play It Loud and Proud: Party rocker Andrew W.K. doesn't bother with pretense. 'Why would I whisper when I can scream?' he asks". Los Angeles Times. p. F13. (subscription may be required or content may be available in libraries)
- Room, National Geographic Press (2016-05-25). "Rishi Nair of Florida Wins 2016 National Geographic Bee and $50,000 College Scholarship – National Geographic Society Press Room". Retrieved 2016-07-22.
- "International Zoo Yearbook", vol 28, 1988.