As power continued to return in parts of the U.S. following the biggest electrical blackout in North American history, plants started the process of trying to return to normal. DaimlerChrysler AG's Chrysler unit said as many as 23 of its 32 North American auto and parts factories were briefly idled by power outages, Bloomberg reported. General Motors Corp. and Ford Motor Co. also said some plants were disrupted.In addition, auto plants in Ontario run by Toyota Motor Corp. and Honda Motor Co. were shut down.Delays in production could hurt truckers who rely on hauling vehicles and vehicle parts. Trucks could also be affected by the large number of airports that were forced cancel or divert passenger and cargo flights.On the New York Mercantile Exchange, September crude oil rose 34 cents to $31.43 a barrel on Friday. The blackout shut electronic trading on NYMEX for almost six hours before it resumed at 10:30 p.m. New York time yesterday.Nymex gasoline for September delivery rose as much as 3.45 cents, or 3.4%, to 101 cents a gallon in after-hours trading, the highest price since March 18, two days before the start of the war in Iraq, Bloomberg said.Plants in the United States and Canada shut down about 451,000 barrels a day of processing at a time when refiners need to boost production to meet gasoline demand during the U.S. driving season, Bloomberg said. Keith Morris, an oil analyst at BNP Paribas in London, told Bloomberg that the blackout would be “catastrophic” for gasoline inventories.The blackout hit shortly after 4 p.m. New York time on Thursday, causing the loss of 61,000 megawatts of power, more than twice that of any previous North American outage, according to the North American Electric Reliability Council. There was a minimal effect on border crossings between the United States and Canada, Dennis Murphy, spokesman for the Homeland Security Department, told AP. The Detroit-Windsor tunnel linking Michigan to Ontario was closed for about 30 minutes after the blackout occurred, AP said.