How heat waves can scorch the U.S. economy

The triple-digit temperatures roasting the Pacific Northwest under a lingering heat dome are also starting to hurt the region's economy.

In Portland, Oregon, temperatures forced the city's streetcar system to shut down as power cables melted and the heat strained the power grid. Near Seattle, roads cracked along stretches of a major interstate and a public pool shut because air quality was dangerous. Some restaurants closed to protect kitchen staff in a region where fewer than half of homes have air conditioning.  Avista, a utility that serves parts of Washington and Idaho, instituted rolling outages Tuesday as surging electricity demand because of the extreme temperatures strained power grids.