See if your library has Ancestry or try the FamilySearch.org for what is online. He filed a WWI Draft Registration Card June 5th 1917 in Jackson Co MO he was a St RY motorman for Kansas City Rys Co. Said he was born in Springfield, MO. And is exempt because he was under a $2500.00 Bond to answer charge of perjury to the State of MO.
He is listed as Miller Rowden in 1900 census Springfield Ward 7, Greene County, MO in parents household with a little brother Lewis R. .
1910 the Rowden family is listed as Roden in Greene Co MO and it looks like there were only the 2 sons still living, Miller and Louis R.
In 1930 census he is listed as Milliard Rowden and is in the Coco Solo Air Station, Cristobal Dist, Panama Canal Zone
The State of Missouri has an online Soldier's Records for WWI and Millard Rowden is listed as Army/Marine.http://www.sos.mo.gov/archives/soldiers/#soldsearch
They also have images of Death Certificates 1910-1961 and it looks like the brother Lewis R in 1900 census died 1932, was single so no descendants there. DC also names parents, who also have dcs, Sat and Alma Rowden all died in Greene County. http://www.sos.mo.gov/archives/resources/deathcertificates/#...
For a obit you might try the San Diego County Library reference desk. Their website may give you details in asking and any fees.