U.S. consumer confidence rose in April to the highest level since September 2008, just as the financial crisis escalated, a private research organization reported Tuesday. The Conference Board said its consumer-confidence index rose to 57.9 this month from 52.3 in March. The April reading is the highest since a reading of 61.4 in September 2008, when the financial crisis intensified with the collapse of investment bank Lehman Brothers, sending confidence plunging the following month. The consumer-confidence index-which measures how consumers feel about business conditions, the labor market, and the next six months-and been recovering unevenly since hitting a record low of 25.3 in February 2009. Economists closely watch consumer-confidence indexes for clues on consumer spending, which accounts for about 70 percent of U.S. economic activity. Despite April's improvement, the reading is far from what is considered healthy. A reading above 90 indicates a healthy economy, and one above 100 reflects strong growth.