Okay, this is really old, but your other post on the Hopp board got me curious! In the 1920 census for Ward County North Dakota, there is a William Hopp with wife Anna, both 36. She reported her birthplace as New York, parents born Germany, which is the same as Anna Mettenhouse in 1900. In 1920, William and Anna are living in Mountrail County, North Dakota. Anna Hopp died in Mountrail County July 20, 1921. Might be worth checking out!
https://secure.apps.state.nd.us/doh/certificates/deathCertSe...
(re: your opinion on Anna being hard to live with, maybe she was just really bad at picking men, she was only 16 at her first marriage)!