Miller was the Kansas secretary of transportation from 2003 to 2012, making her the first female and longest serving transportation secretary of that state. She was appointed by former Governor and current Health and Human Services Secretary Kathleen Sebelius and then retained by Gov. Sam Brownback.
Miller is currently a senior associate at Cambridge Systematics, a transportation consultancy firm located in Cambridge, Mass. The company's clients include the Federal Highway Administration, Federal Transit Administration, Federal Motor Carrier Safety Administration, 44 state transportation agencies, Amtrak, CSX, Norfolk Southern and the Long Island Rail Road.
Before being appointed secretary, Miller was the director of planning and development at KDOT from 1986 to 1997 and was previously a planner at HNTB Infrastructure Solutions.