As oil prices have plummeted to levels never before seen, a rift has opened among the companies that extract crude. Some of them say state regulators should force producers to pump less in the hopes such regulation will raise prices. Others say no, just let the market do its job. While Texas, an oil-producing behemoth, is weighing the controversial idea of imposing limits, New Mexico, now an oil powerhouse in its own right, has largely stayed out of that debate. Depending where oil prices go and what other states decide to do, there may come a point when the state...