“They may have kept one hour (or less)”
To this day, Jews in the Netherlands keep one hour. Even the Sefardic Jews there adopted that Ashkenazic ruling.
And that should be the ruling in America, too, because for the first 143 years of Jews in America all the communities followed the Dutch Sefardim. The Ashkenazim broke with the mesorah starting in 1797 in Philadelphia. There should be no surprise that there is not a single Ashkenazi congregation in America that was started prior to 1850 that is still Orthodox, while two remaining Sefardic congregations from colonial times remain halachic. (The word “orthodox” had not yet been applied to Judaism at the time they were founded.)