Files with tgr file extension might be found as older Tiger Line files. Some sort of GIS format.
TGR file extension - Tiger Line data
What is tgr file? How to open tgr files?
File type specification:
The tgr file extension is mainly related to Tiger Line products from U.S. Census Bureau. TIGER is short for Topologically Integrated Geographic Encoding and Referencing.
Seems like older format replaced by newer standards.
This tgr file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.