[3] Lyndon was founded in 1869 after the land in the area was taken from the Sac and Fox Nation by the government for homesteading.

[6] According to the United States Census Bureau, the city has a total area of 0.83 square miles (2.15 km2), all land.

[7] The climate in this area is characterized by hot, humid summers and generally mild to cool winters.

The 2020 United States census counted 1,037 people, 424 households, and 291 families in Lyndon.

There were 454 housing units at an average density of 509.0 per square mile (196.5/km2).

27.1% of households consisted of individuals and 13.7% had someone living alone who was 65 years of age or older.

There were 464 housing units at an average density of 559.0 per square mile (215.8/km2).

29.1% of all households were made up of individuals, and 13.8% had someone living alone who was 65 years of age or older.

24.8% of all households were made up of individuals, and 15.5% had someone living alone who was 65 years of age or older.

The community is served by Lyndon USD 421 public school district.