The New York Post set a single-day record of 1.1 million sales on 11 August 1977 .
By that time , circulation of the all-day Post soared to a peak of 962,000 , the bulk of the increase attributed to its morning edition ( It set a single-day record of 1.1 million on August 11 , 1977 with the news of the arrest the night before of David Berkowitz , the infamous `` Son of Sam '' serial killer who terrorized New York for much of that summer ) .
New York Post