The San Joaquin Valley officially shares the distinction of having the worst air quality in the nation with the Los Angeles region. Poor air quality is affecting the region's residents, public health, and the economy. Without further action, the problem will only get worse. The population of the region is growing more rapidly than in any other air basin in the state. This growth brings with it increases in vehicle miles traveled and urbanization, both of which counteract progress in emission reductions. As a result, the valley risks becoming the nation's dirtiest region. Strong action by local, state, and federal officials can put the San Joaquin Valley back on the road to clean air, but it will take a coordinated effort and strong leadership that has, to date, been lacking.