The documentary record is less tidy.
What the sources actually say
No builder's inscription, no foundation contract, and no dated dedicatory plaque survives for the wooden synagogue at Zabłudów. The figure 1637 derives principally from the secondary literature on Polish wooden synagogues, consolidated most influentially in Maria and Kazimierz Piechotka's Bóżnice Drewniane (Wooden Synagogues, 1959), which drew on municipal and ecclesiastical records as well as earlier scholarly summaries. The Piechotkas treated 1637 as the likeliest date of construction, but characterised it as approximate rather than proven. Their broader survey made clear that for many buildings of this type, the founding date rests on a grant of privilege or a town council record rather than a construction document, and that such records name permission, not completion.
The distinction matters. A privilege authorising a Jewish community to erect a house of prayer could precede the building's physical existence by years. Conversely, a community might begin construction before formal permission was recorded, regularising its status after the fact. Neither sequence was unusual in the Podlaskie towns of the seventeenth century, and Zabłudów was not exceptional in leaving that gap unresolved.
Polish State Archives in Białystok hold pre-war municipal registers and ecclesiastical survey material relating to the Zabłudów area, but the relevant early modern documents are fragmentary. No archival record currently in the public domain specifies a construction year with unambiguous reference to the timber synagogue as a completed structure. The 1637 figure, in short, is an informed scholarly inference — the best available answer, not a confirmed fact.
What can reasonably be said
Dendrochronology — tree-ring dating applied to structural timbers — could in principle resolve the question, but no such analysis was conducted before the building's destruction. The measured surveys carried out by students of Warsaw University of Technology in the 1920s recorded the building's geometry and fabric in meticulous detail but included no dating analysis of the timber. Those drawings are now the primary material record.
What the architectural evidence does support is a mid-seventeenth-century date in a general sense. The plan type, the structural system of notched-corner log construction, and the relationship of the prayer hall to its vestibule are all consistent with comparable buildings documented elsewhere in the region at that period. The Tykocin synagogue, a masonry comparator completed in 1642, provides some regional chronological anchoring. Within that frame, 1637 is plausible. It should be cited with the qualifier its sources actually carry: circa, not certain.