English: A map describing the principal dialect groupings of the closed West Germanic dialect continuum between German, Frisian, Low Franconian / Netherlandic and Low German around the year 1900. Based on:

• P. Wiesinger: Die Einteilung der deutschen Dialekte. In: Dialektologie. Ein Handbuch zur deutschen und allgemeinen Dialektforschung, series: HSK 1.2, Berlin, New York, pp. 807-900
• W. König: dtv-Altas Deutsche Sprache, 2019, Munich, pp. 230.
• J. Goossens: Deutsche Dialektologie, Walter de Gruyter, 1977, pp. 48.
• W. Heeringa: Measuring Dialect Pronunciation Differences using Levenshtein Distance, University of Groningen, 2009, pp. 232-234 ([1]).

• Note: The majority of the map is based on that of Wiesinger, the former eastern areas of the German language are principally based on König. When in conflict in one another, priority was given to Wiesinger.

Legend: Lines

• The thin white/black dashed line represents the area in which two Dachsprachen are present: Standard Dutch (alongside Standard West Frisian) in the Netherlands, and Luxemburgish (alongside Standard German) in Luxemburg.
• The thick white line represents Standard Language isogloss (Goossens) between the dialects for which Dutch is the standard language (to the left of the line) and those for whom German is the standard language (right of the line).
• Striped lines indicate transitional dialects.

Low Franconian varieties: (purple)
1. Central Dutch
2. West Flemish
3. Brabantic
4. Limburgian
5. Lower Rhenish

Frisian varieties: (orange)
6. West Frisian
7. Saterlandic (last remnant of East Frisian)
8. North Frisian

Low German varieties: (blue)
9. Overijssel
10. Gronings
11. Westphalian
12. Northern Low German
13. Eastphalian (one yellow part inside is Erzgebirgisch in part of the Harz)
14. Mecklenburg-Pomeranian
15. Brandenburgish (the yellow part inside is Berlinian in Berlin)
16. Middle Pomeranian
17. Eastern Pomeranian
18. Low Prussian

Middle/Central German varieties: (yellow)
19. Ripuarian
20. Luxemburgish (closely related to Moselle Franconian, but different written standard)
21. Moselle Franconian
22. Rhine Franconian
23. Central Hessian
24. Northern Hessian
25. Eastern Hessian
26. Thuringian
27. Northern Upper Saxon
28. South Märkisch
29. Upper Saxon
30. Silesian
31. High Prussian

Note 1: The empty part near 25, 26, 27 isn't a lake but Sorbian, a Slavic variety.
Note 2: Transylvanian Saxon spoken in Transylvania (Romania) is missing on this map.

Upper German varieties: (ochre)
32. East Franconian
33. North Bavarian
34. Central Bavarian
35. South Bavarian
36. Swabian
37. Low Alemannic
38. Middle Alemannic
39. High Alemannic
40. Highest Alemannic

German language pockets in Eastern and Southern Europe: (lila)

Cp.:

• File:German dialect continuum in 1900 (according to Wiesinger, Heeroma & König).png
• File:Map of German dialects (according to Wiesinger, Heeroma & König).png
• File:West Germanic dialect continuum (according to Wiesinger, Heeroma & König).png
• File:Deutsch-Niederländischer Sprachraum (nach Werner König).png