Iowa Attorney General Tom Miller and attorneys general from 20 other states are investigating the proposed merger of United Airlines and U-S Airways.Miller believes the United/U-S Airways merger would trigger others, and leave Americans with just three major airlines. Miller says that would be bad news for states like Iowa, which already have sky-high airfares.Miller says the attorneys general plan to submit a report to the U-S Justice Department, but if federal officials take no action against the merger, Miller and the other state officials may sue on their own. Miller made his comments during taping of the Iowa Public Television program, “Iowa Press.”