McMechen is located at . According to the United States Census Bureau, the city has a total area of, of which, is land and is water.
Climate
The climate in this area is characterized by relatively high temperatures and evenly distributed precipitation throughout the year. According to the Köppen Climate Classification system, McMechen has a Humid subtropical climate, abbreviated "Cfa" on climate maps.
As of the census of 2010, there were 1,926 people, 856 households, and 516 families living in the city. The population density was. There were 971 housing units at an average density of. The racial makeup of the city was 97.7% White, 1.0% African American, 0.2% Native American, 0.2% Asian, 0.1% from other races, and 0.8% from two or more races. Hispanic or Latino of any race were 1.0% of the population. There were 856 households of which 26.4% had children under the age of 18 living with them, 40.4% were married couplesliving together, 14.7% had a female householder with no husband present, 5.1% had a male householder with no wife present, and 39.7% were non-families. 35.0% of all households were made up of individuals and 16.5% had someone living alone who was 65 years of age or older. The average household size was 2.24 and the average family size was 2.88. The median age in the city was 41.6 years. 20.9% of residents were under the age of 18; 8.3% were between the ages of 18 and 24; 24.7% were from 25 to 44; 28.4% were from 45 to 64; and 17.7% were 65 years of age or older. The gender makeup of the city was 48.6% male and 51.4% female.
2000 census
As of the census of 2000, there were 1,937 people, 865 households, and 559 families living in the city. The population density was 3,352.4 people per square mile. There were 953 housing units at an average density of 1,649.4 per square mile. The racial makeup of the city was 98.55% White, 0.36% African American, 0.10% Native American, 0.10% Asian, 0.15% from other races, and 0.72% from two or more races. Hispanic or Latino of any race were 0.41% of the population. There were 865 households out of which 24.6% had children under the age of 18 living with them, 46.5% were married couples living together, 14.6% had a female householder with no husband present, and 35.3% were non-families. 33.1% of all households were made up of individuals and 19.0% had someone living alone who was 65 years of age or older. The average household size was 2.23 and the average family size was 2.81. In the city, the population was spread out with 20.8% under the age of 18, 7.0% from 18 to 24, 23.5% from 25 to 44, 26.0% from 45 to 64, and 22.8% who were 65 years of age or older. The median age was 44 years. For every 100 females, there were 89.2 males. For every 100 females age 18 and over, there were 81.9 males. The median income for a household in the city was $27,179, and the median income for a family was $33,080. Males had a median income of $27,357 versus $16,862 for females. The per capita income for the city was $14,935. About 15.6% of families and 20.6% of the population were below the poverty line, including 43.1% of those under age 18 and 9.6% of those age 65 or over.
