Complex sentence: CNR (CN after the 1960s) continued to operate the Portland-Sherbrooke line as its Berlin Subdivision but traffic continued to decline and by the late 1980s, following deregulation of the U.S. railroad industry, it became a candidate for divestiture to a shortline operator.
Split into simpler sentences: CNR (CN after the 1960s) continued to operate the Portland-Sherbrooke line as its Berlin Subdivision, but traffic continued to decline. By the late 1980s, following deregulation of the U.S. railroad industry, it became a candidate for divestiture to a shortline operator.