[All information below is accurate as of Jan 9, 2015]
The St. Louis Public Library Obituary Search
The St. Louis City Public Library has created a searchable index for St. Louis Post Dispatch obituaries currently covering the years: 1880-1930, 1942-1945, 1960-1969, and 1992-2011.
In addition to the search engine, they have an index-by-year that can be browsed, leading to the same entries.
Note: This indexes 'burial permit' listings as well as obituaries. The burial permit listings contain significantly less information than an obituary. Usually just a name, date and address.
St. Louis Post Dispatch - 1975-1977
An index for these years can be found on Bob Doerr's website. He was the editor of the Missouri State Genealogical Association Journal from 1992 through September of 2009, when he passed away. His website remains functional.
St. Louis Post Dispatch Archives 1988-Current
The Post Dispatch website allows you to search obituaries back to 1988, and then it gives you the option of downloading the obituaries through NewsLibrary.com, which has several rates, starting at $2.95 for single articles, and progressing to a 1 year pass for 500 articles at $199.95.
Note: The search engine doesn't capture every obituary, so it is useful to check the indexes above for those after 1992.
St. Louis Globe Democrat - 1860-1861, 1880, 1881, 1883
While this doesn't cover many years, the St. Louis County Library has begun an index for the St. Louis Globe Democrat.
Globe Democrat Morgue (Clippings File) 1930-1986
The St. Louis Globe Democrat, upon their demise, donated their large "Clippings File" to the University of Missouri at St. Louis. UMSL has begun to index the collection. The collection contains many obituaries, as well as other genealogical gems.
St. Louis Argus Obituaries (1915-1919, 1921-1927, 1942-1945)
"The ST. LOUIS ARGUS serves as a valuable resource for deaths in the local African-American community, especially during the early 20th century, when obituaries or death notices for this segment of the population were generally not carried in major area newspapers."The Westliche Post Obituaries
The St. Louis County Library has an index for The Westliche Post, a German language newspaper
The index currently covers the years 1878-1893, with a handful of gaps mentioned on their page.
On the other side of the Mississippi river
Belleville, Illinois Daily Advocate
An index for vital statistics (Adoptions, Births, Baptisms, Marriages, Divorces, Deaths) 1927-1954 at the St. Clair Genealogical Society.
The St. Clair Genealogical Society also has indexes for the Belleville News Democrat (1994-2007), Freeburg Tribune (1904-1939; 1999-2012), Lebanon Advertiser (1917-1921), and the Millstadt Enterprise (1897-1949). Scroll down their homepage for links to each of them. There is a site-search box at the bottom of the page, though it doesn't include the Daily Advocate index.
How to Get a Copy of the Obituary
If you do live in St. Louis, you can find the obituary in the newspaper microfilm archives at either the St. Louis County or St. Louis City headquarter libraries. (Only the County library has The Westliche Post on microfilm. Both have the St. Louis Argus, but the County library doesn't appear to have the years 1942-1945.)
If you don't live in the St. Louis area, the policies at the two libraries differ slightly. The St. Louis County Library says staff may be able to look up the microfilm for a single article 'if time allows,' and if you know the name of the newspaper, and specific date. If they are able to help, the cost for making copies and mailing is minimal.
The St. Louis City Library reference policy doesn't specify beyond saying, "The level of research assistance provided varies according to the availability of staff, the staff and customer’s knowledge of the subject, the volume of other customer requests, the depth of the collection, the complexity of the question and the time frame in which the information is needed."
The Mercantile Library at UMSL is willing to conduct research in the Globe Democrat's clipping files (as well as their other collections) but their pricing structure begins at $66/hr (15 min increments), with photocopies extra.
For the Illinois newspapers, the Belleville Public Library is the place to go.