Blois, Andover and Lawrence Express' Lawrence, Mass. office was at the Merchants Co-op Express offiice in Lawrence. Merchants Co-op cancelled the stamp below:
From the 1897-98 Andover, Massachusetts directory comes the first image of this post and a reference to the Merchants Co-op Express. Not sure how the Blois, Andover, and Lawrence Express relates the Merchants other than the use of an office.