Soviet troops occupied Latvia on 17 June 1940. The LPSR - short for Latvijas Padomju Sociālistiskā Republika (Latvian Soviet Socialist Republic)- is established on 21 July. This Republic is incorporated in the Soviet Union on 5 August 1940 as 15th republic of the USSR. On 22 June 1941 start the war between Germany and Russia. Riga is occupied by Germany on 1 July.
More about the LPSR in Wikipedia.

• Machine postmarks

Machine postmarks

The two machines for the application of postmarks, in function in independent Latvia, were used further in the soviet period 1940-1941.

In the beginning the Latvian postmarks were used, but later -from October 1940- you see the postmark changing: bilingual indication of the place and the soviet star. As serial letters were then used: А and -as here- Б. The type here with serial Б is a sub-type, used 11-11-1940 until 19-12-1940, with the flag-waves first going down (for the other type -with the flag first going up: see the card at the bottom of this page). Original print size of this image: 16,391 x 11,718 cm (is something more as the postal item) This picture and all pictures below on this page, if not mentioned otherwise: scanned about 300 dpi. Then set right and cut out - noted the actual print size-, resized 25 % of this image and saved as jpg.

The postmark, resized 50 %:

Card with machine-postmark, but now the LPSR-postage stamp is used. Original print size of this image: 13,648 x 8,695 cm (is something more as the postal item)

On the other side, a nice view:

The postmark, resized 50 %

Another card with machine-postmark, used in the LPSR-period. Original print size of this image: 13,801 x 8,797 cm (is something more as the postal item). The postmarks, resized 50 %: The arrival-postmark of Vecmilgrāvis is still Latvian: with LATVIJA

The type with serial letter Б, used between 27-12-1940 and 14-6-1941, sub-type with the flag first going up.

The picture on the other side of the card

Continued