BILLINGS, Mont. -

Federal officials have identified 20 parcels of public lands in 10 states they say could be suitable for bison relocated from Yellowstone National Park.
    
The locations include areas as diverse as Arizona's Grand Canyon National Park, an Iowa wildlife refuge and a North Dakota national historic site. They were named by the Department of Interior in a report on bison conservation released Monday.
    
Yellowstone had roughly 4,600 bison at last count. The population periodically spills into neighboring Montana, triggering large-scale slaughters of the animals to prevent the spread of disease.
    
A pilot program to relocate Yellowstone bison has struggled to overcome livestock industry opposition in Montana.
    
If such a program were made permanent, federal officials say it could be up to a decade before more animals were relocated.