The Wall Street Journal examines Phoenix as a proving ground for resolving how utilities, ratepayers, and data center operators split the cost of grid upgrades required by accelerating AI infrastructure buildout. Arizona utilities are negotiating large power agreements with hyperscalers while regulators weigh whether residential customers should bear any portion of transmission and generation investments. Phoenix hosts some of the densest concentrations of data center capacity in the U.S., making cost-allocation decisions there a likely model for other markets. Rate cases and legislative action in Arizona are expected to set precedents over the next 12 to 18 months.