Governors in 18 of the 50 U.S. states agreed to build health-insurance exchanges, a final tally that leaves the federal government with the duty of running marketplaces for the majority of the nation through 2014.

Idaho, Nevada and Utah were among the states that submitted blueprint applications to the Obama administration by the Dec. 14 deadline to create exchanges for residents to shop for insurance as part of the Affordable Care Act, the Department of Health and Human Services said today. Governors who opted out said they balked at the federal regulations they would have to adhere to and long-term costs they would have to bear.