Denver-area officials are haggling over whether projected growth boundaries for the metro area should be redrawn, with one-point-five million people predicted to come in over the next three decades.
The Denver Regional Council of Governments created its urban growth boundary to limit development, sprawl and traffic.
It was part of efforts to meet federal clean air standards.
The state could face sanctions, including loss of federal highway funds, if it doesn't meet the standards.
Some members of the regional group think extending the boundaries will encourage sprawl, but others say the boundary is voluntary.
Environmentalists argue that expanding the boundary will make it meaningless.