Automakers typically close plants around the July 4 holiday to update cars and trucks for the new model year and maintain the machinery.
But Chrysler spokeswoman Jodi Tinson says the Jefferson North factory in Detroit that makes the SUVs will stay open all summer. The plant is working overtime on two shifts and running two of every three Saturdays.
Chrysler sold nearly 38,000 Grand Cherokees from January through March, up 44 per cent from a year ago. Durango sales were up 33 per cent at just over 11,000.
Tinson says Chrysler can make changes for the 2013 model year while the plant is running.