Pepco Region President Thomas Graham thanked customers for their patience, 46 days after more than 480,000 Pepco customers lost power — some for more than a week — following the June 29 derecho.

In a letter that arrived in customers’ mailboxes this week, Graham touted the company’s force of more than 3,000 workers who were involved in restoring power in the days following the storm and emphasized the destructive force of the derecho, a type of storm that gets its name from its straight-line winds.