Google Fusion Maps
Old Thanksgiving Map
Locations in mentions of Thanksgiving from 1890-1920 are located primarily across America with concentrations near New York City, Los Angeles, and London. This reflects the celebration of the holiday in that time period in that the celebration was disproportionately in highly populated areas. Due to the higher concentration of people there, there will naturally be more references to these areas, but the documents themselves reveal that there is more than population count at play. The celebration was frequently a religious affair, with celebration mostly taking place en masse in activities organized by churches. Thanks were given, not to family members the like as is often done today, but directly unto God - many sources mentioning Thanksgiving then include instructions on things like " Prayer with Thanksgiving to Almighty God" or other ways of "Thanksgiving" unto God. People are cited as spending the night in "Prayer that the year 1890 may be one of...prosperity."
The frequency of popularity in Britain (mostly London) does not imply international celebrations so much as yet more adherence to religious tradition and organized celebration. Many of America's religious traditions are derived from English roots, and the connection was only more strong 100 years ago. The sources do not mention England or its people celebrating the aspects of Thanksgiving we may associate with it today (consumption of turkey, a gathering of family, etc.) but simply rather mentions of religious thanks giving on the day.
Overwhelmingly, the conclusion to draw of the reception of Thanksgiving 100 years ago is that religion was very heavily involved. Even if one is to assume the term "Thanks giving" is used to imply a general giving of thanks in a religious sense that has nothing to do with the holiday named the same thing, the holiday would still be religious - most of the other sources mention sermons being preached "on Thanksgiving Day" or reverends doing something on the day. There were aspects of the gathering of communities and festivity as we would think of in today's Thanksgiving, but for the most part, Thanksgiving was a formal and religious affair that people attended out of obligation, not celebration.
Modern Thanksgiving Map
Scrolling reveals the modern map to have many locations listed across the globe, primarily in Britain and other parts of Europe. This reflects how Thanksgiving has changed over the years in that it reflects its transformation into a more social and secular celebration. The occasion is still almost exclusively celebrated by Americans, but those Americans include their friends from other countries or will include their friends while in other countries to celebrate it. There is more focus on enjoying the holiday rather than giving it due respect.
In addition, the frequency of occurrences on the East Coast also has implications for the changed celebration of the holiday. The city of New York is mentioned several times in reference to the "Macy's Thanksgiving Day Parade" - effectively a continuous series of advertisements for various companies, but becoming increasingly accepted as a Thanksgiving tradition. In other documents, there are also many documents to "Thanksgiving sales" or "special Thanksgiving offers" - evidence that the celebration is becoming just as much of a celebration of capitalism and revelry as a celebration of friendship and family.
Overall, the change in the celebration of Thanksgiving as depicted by the modern menus reflects how the reception of the holiday has changed, whether celebrated privately with friends or publicly in a commercial event. People generally tend to focus on maximizing enjoyment of the holiday, both by enjoying it in a more relaxed and secular manner than was done 100 years ago or by using it as an excuse for excess and purchasing. Either way, it is a less rigid affair, and one with a greater spread and variety of celebration.