Westphalia is a city in Anderson County, Kansas, United States. As of the 2020 census, the population of the city was 128. Westphalia was plat…Westphalia is a city in Anderson County, Kansas, United States. As of the 2020 census, the population of the city was 128. Westphalia was platted in 1880 when the railroad was extended to that point. It was originally built up mainly by Germans.