Mason is home to Kings Island amusement park and one of the largest tennis stadiums in the world, the Lindner Family Tennis Center, home of the Western & Southern Open, one of the world's top tennis tournaments for both men and women.
In 1835, a petition was sent to the federal post office to correct the name of the town. The town had been listed as Kirkwood, possibly an error because the postmaster at the time was named William Kirkwood. When village officials were informed that there was another Palmyra in Ohio, the name was officially changed to "Mason."
In February 1997, Mason withdrew from surrounding Deerfield Township by forming a paper township called Mason Township.
On October 25, 2021, Mason City Council passed an ordinance to criminalize abortions within the city limits by a vote of 4 to 3. No abortion providers currently operate within the city limits. The ordinance was later repealed.
The city is in the Mason City School District. Mason is served by one interstate, I-71.
There were 11,016 households, of which 44.5% had children under the age of 18 living with them, 63.4% were Marriage living together, 8.4% had a female householder with no husband present, 2.7% had a male householder with no wife present, and 25.5% were non-families. 22.4% of all households were made up of individuals, and 8.3% had someone living alone who was 65 years of age or older. The average household size was 2.77 and the average family size was 3.30.
The median age in the city was 38.4 years. 30.8% of residents were under the age of 18; 5.7% were between the ages of 18 and 24; 26.1% were from 25 to 44; 27.4% were from 45 to 64; and 9.9% were 65 years of age or older. The gender makeup of the city was 48.5% male and 51.5% female.
There were 7,789 households 45.2% of which had children under the age of 18, 67.5% had Marriage living together, 6.8% had a female householder with no husband present, and 23.2% were non-families. 20.0% of all households were made up of individuals, and 6.7% had someone living alone who was 65 years of age or older. The average household size was 2.80 persons and the average family size was 3.27 persons.
In the city, the population was spread out, with 32.1% under the age of 18, 5.1% between 18 and 24, 35.3% between 25 and 44, 19.1% between 45 and 64, and 8.4% over the age of 65. The median age was 34 years. For every 100 females, there were 95.7 males. For every 100 females age 18 and over, there were 92.4 males.
Mason is home to seven city parks which cover about 300 acres and include fishing lakes, walking trails, ball fields, tennis courts, picnic shelters and playgrounds. The 199,000 square-foot multi-use Mason Community Center, which opened in 2003, is one of the largest public recreation facilities in the state. It has two pools, gymnasium, field house, fitness center, walking track, senior center, exergames, climbing wall, and classroom and meeting areas. A continually expanding network of bike paths connects neighborhoods to schools, parks and downtown.
The Mason Veterans Memorial, adjacent to the Mason Municipal Center, was dedicated on Saturday, November 8, 2003. The late Neil Armstrong, a Korean War veteran and the first man to walk on the moon, was the guest of honor. The main feature of the memorial is a set of 10 pillars representing the 10 major conflicts in American history. The height of each pillar is proportional to the number of casualties in the war. The memorial also features an eternal flame.
The Mason Police Department is accredited by the Commission on Accreditation for Law Enforcement Agencies (CALEA). The department employs 39 full-time sworn police officers, including the chief, two assistant chiefs, four lieutenants, and four sergeants. Additionally, the department has seven non-sworn support personnel, including two court security officers. The City of Mason Police Department operates 17 fully equipped marked police cruisers, eight unmarked police cars, and one D.A.R.E. car. In addition, the department operates several special purpose vehicles, including motorcycles, bicycles, and Segways.
The Mason Fire Department has more than 50 fire and emergency medical personnel, including the fire chief, four deputy chiefs, administrative staff, fire inspectors, and full or part-time firefighters. Firefighters are also trained as paramedics or emergency medical technicians (EMT's). The department has two pumpers, one 100-foot ladder truck, one 100-foot tower ladder, one heavy rescue/hazardous materials truck, four paramedic ambulances, one paramedic response car, and additional staff vehicles. These vehicles respond from one of the city's two fire stations.
Mason's largest employers include Procter & Gamble's Mason Business Center, the headquarters of Luxottica and Cintas corporate headquarters. Other notable companies with large operations in Mason are Mitsubishi Electric, L-3 Communications, Heinz., and Prasco Laboratories
Over 500 businesses operate in Mason's 18 square miles. High-tech companies, corporate headquarters, and light industries are particularly attracted to Mason. More than 90 corporations have headquarters or manufacturing operations in Mason's 24 commerce parks.
Newspapers and websites covering Mason include the Cincinnati Enquirer, MasonBuzz.com and Today's Pulse.
Due to Mason's proximity to Dayton, approximately 30 miles north, Dayton radio and television stations also are easily received in the area. However, only two Dayton television stations, WHIO-TV (CBS) and WPTD (PBS), are carried on local Time Warner cable.
High school programs in athletics and academics have been successful at the state level, earning team state titles in Division I in:
The district joined the Greater Miami Conference (GMC), the public school league with the largest enrollments in Greater Cincinnati, in 2007–08, and has won the All Sports Trophy in each of its seven years.
Mason has five public schools: Mason Early Childhood Center (PK-2), Mason Elementary School (grades 3-4), Mason Intermediate School (grades 5-6), Mason Middle School (grades 7-8), and William Mason High School. Mason also has a community center that connected to the high school. The last building to open was the Mason Elementary ("ME") which opened in 2019. Mason City Schools feature broadband networks while supporting over 4,600 classroom computers There are approximately 2.2 students per computer in the district. The district also supports individual teacher pages for posting work assignments and class information (such as Edline and Mason Mason Comets). Parents have secure web access to student information. The most recent building project was in 2018–19 with an addition to Mason Early Childhood Center, which was built in 2006, and the division of Mason Intermediate into Mason Intermediate and the new Mason Elementary School, along with a total revamp of the Mason Middle Schools interior. The addition included a new gym for Mason Early Childhood Center, the relocation of 3rd grade to the new Mason Elementary, and a remake of the interior of Mason Middle.
Mason is also home to Sinclair Community College's Courseview Campus, which opened in 2007. The facility is on 75 acres near I-71. As of fall 2013 it has a capacity of 2,500 students and offers 17 degree and 18 certificate programs. In early 2013 Sinclair announced that it expects the Courseview Campus to serve 10,000 students within the next 25 years.