The latest tally falls below the prior ebb of 809 units recorded last week, and less than half of the year-ago figure of 1930.
The number of rigs exploring for oil dropped to 605, down by nine from the week before.
The count of those exploring for gas stood at 189, down six from the week-ago figure.
Oklahoma and Texas were hit hardest by decreases this week, down six and four respectively to nine and 353.
Texas
