Company Names, addresses, dates: ¹
  Union-Street Pharmacy, 432 N Union Street, Danville VA (c.1902-c.1906)
  Union Drug Co, 231 N Union Street, Danville VA (c.1927-c.1930)

Notes:
The Union Drug Co shows up in city directories from 1927, 1929, and 1930. It's not listed in the 1921 or 1931 directories.

The Union-Street Pharmacy is probably no relation to the "Union Drug Store", other than the similarity of the name. But here's what I found about the Union-Street Pharmacy:

It shows up in the city directories in 1902,1904, and 1906, at 432 N. Union Street. The proprietor was George W. Bull. In fact, the 1904 city directory listed 2 separate drugstores at 432 N Union street: one named the "Union-Street pharmacy" and the other named "George W Bull". The 1908 city directory said that George W. Bull was working clerk for the J.C. McFall drug store. Bull doesn't show up in Danville city directories after that.

This is a clear 3.0" BIM bottle embossed: vertical: Union Drugstore / INC / DANNVILLE, VA. The bottle has vertical ribs along the sides.