Picture of exposition during 40 Hours at Kenrick-Glennon Seminary
This weekend, we have been participating in the 40 hours devotion at the Seminary. The Eucharist is exposed for 40 hours throughout the weekend (day and night), and reposed during Masses. In the United States, the 40 Hours Devotion has an interesting history:
"The first to hold [40 hours] devotions with any degree of regularity was Bishop John Nepomucene Neumann of Philadelphia. In 1857 Archbishop Patrick F. Kenrick obtained from Pius IX the modifications which are in use in the United States. A plenary indulgence is granted to all persons who, being truly contrite and having received the Sacraments of Penance and the Eucharist, visit a church in which the exposition is held on one of the three days and pray there for the intentions of the Holy Father."
(Source)
*Note: The Archbishop Patrick F. Kenrick mentioned above is not the same as the 'Archbishop Kenrick' (Peter Richard Kenrick) who was in St. Louis - interestingly, though, they are brothers, and both immigrated to the U.S. from Ireland in the first half of the 19th century.