Coat of Arms 

The blazon and significance of the coat of arms of the Archdiocese of St. Louis, as written by William F. J. Ryan to Rev. Msgr. John P. Cody, on September 12, 1946:

Archdiocese of St. Louis Shield

Shield is ornamented with a large gold cross, as the central figure. The Latin cross fleury is displayed in honor of the French origin of the city of St. Louis. This cross is replete with significance; the French missionaires; the penance, fasting, and heroic sanctity of Louis IX of France, saint and King; a commemoration of the true Crown of Thorns and a portion of the Cross of Calvary in Jerusalem, and their reservation in St. Chapelle in Paris; the two crusades of St. Louis.

The crown fleury represents Louis IX as King, rather than as saint.

The tinctures, blue and gold, are those of the arms of Pope Leo XII who established the diocese. A crown, also, is contained in this coat-of-arms of Pope Leo XII.

The bar wavy, of course, is for the Mississippi river.

The silver crescent has a double significance. It is from the coat-of-arms in the Seal of Missouri, and also represents our Blessed Mother, Patroness of the United States under the title of the Immaculate Conception.