Question: Which university founded in 1818 is the oldest university west of the Mississippi River: Saint Louis University or Marquette University? 
Context: Marquette University is a private, coeducational Catholic university located in Milwaukee, Wisconsin, in the central United States.  Established by the Society of Jesus as Marquette College on August 28, 1881, it was founded by John Martin Henni, the first Bishop of Milwaukee. Dr. John J. Pauly became provost of Marquette University in 2008.  He had served as dean of the J. William and Mary Diederich College of Communication at Marquette for two years before becoming provost, and had been chair for nine years of the communications department at Saint Louis University, where he was honored twice for excellence in teaching. KSLU is a Student Media Organization at Saint Louis University (SLU) in Saint Louis, Missouri.  The organization, which is affiliated with the College of Arts & Sciences' Department of Communication, provides "Saint Louis University and the St. Louis community with a student-run, tangible media outlet; providing new music, talk radio, written publication, as well as other student needs".  Its studios and offices are located in the University's Busch Student Center building. Saint Louis University School of Law, also known as SLU LAW, is a private American law school located in St. Louis, Missouri.  It is one of the professional graduate schools of Saint Louis University.  Opened in 1843, it is the first law school west of the Mississippi River.  The school has been ABA approved since 1924 and is a member of the Association of American Law Schools.  Housed in Scott Hall, the law school has the highest enrollment of law students in Missouri .  It offers both full- and part-time programs.  The school is also home to Saint Louis University's Vincent C. Immel Law Library, which is one of the largest law libraries in the state of Missouri.  Supreme Court Justice Clarence Thomas studied for his bar exam at the old Omer Poos Law Library on the main SLU campus. Saint Louis University School of Medicine (SLUSOM) is a private, American Medical School within Saint Louis University.  Located in the city of St. Louis, Missouri, Saint Louis University School of Medicine was established in 1836 and has the distinction of awarding the first M.D. degree west of the Mississippi River. The Saint Louis University Ice Pavilion is a proposed project by Saint Louis University to build an indoor ice and sports facility to be constructed in concert with another project already in progress, the Chaifetz Arena.  The university is planning to build an on-campus ice arena, to be named 'SLU Ice Pavilion.'  The facility will host youth, high school, college hockey as well as special events; it will have a seating capacity of 2,300, and offer four youth hockey locker rooms, Saint Louis University Locker rooms (D1 and D2), four Prep School Locker rooms, conditioning and weight room.  As well as common and quiet study lounges for students and private offices and two private suites to be used for special events and/or VIP use.  The Ice Pavilion will also offer activities such as public skating, figure skating clubs, speed skating clubs, intramural broomball, intramural hockey, curling clubs, and learn-to-skate opportunities for the students and faculty.  The plans for this new Ice Pavilion were in response to the need for a closer facility to the Saint Louis University campus.  The current facility in use, the Summit Center in Chesterfield, MO, is approximately 21 miles away from SLU's campus, with average crowd sizes of 250-400 in attendance. The Saint Louis Billikens are the collegiate athletic teams from Saint Louis University of St. Louis, Missouri.  The Billikens compete in Division I of the National Collegiate Athletic Association (NCAA) as a member of the Atlantic 10 Conference (where they are the westernmost member, and both the first member located west of the Mississippi and in the Central Time Zone).  SLU is heavily rumored to be joining the Big East Conference, which would include more geographically relevant rivals like Creighton (Nebraska), Marquette (Wisconsin), and DePaul (in Chicago).  The school has nationally recognized soccer programs for men and women.  The school has heavily invested in its on-campus athletic facilities in the past twenty years with the creation of Hermann Stadium and Chaifetz Arena.  Chris May is the current director of athletics of the St. Louis Billikens. Richard Raymond Majerus (February 17, 1948 – December 1, 2012) was an American college basketball coach.  He coached at Marquette University (1983–1986), Ball State University (1987–1989), the University of Utah (1989–2004), and Saint Louis University (2007–2012).  Majerus' most successful season came at Utah in the 1997–98 season, when the Utes finished as NCAA national runners-up. Saint Louis College (SLC) is a college in City of San Fernando, La Union, Philippines.  It was founded by the Congregatio Immaculati Cordis Mariae (CICM).  There are also sister schools of SLC, like Saint Louis University(SLU) in Baguio, University of Saint Louis Tuguegarao (USL) in Tuguegarao City, Saint Louis College of Cebu in Mandaue, Cebu, Saint Mary's University (Philippines) in Bayombong, Nueva Vizcaya, and Maryhill School of Theology in Quezon City. Saint Louis University (SLU, ) is a private Roman Catholic four-year research university with campuses in St. Louis, Missouri, United States and Madrid, Spain.  Founded in 1818 by the Most Reverend Louis Guillaume Valentin Dubourg, It is the oldest university west of the Mississippi River and the second-oldest Jesuit university in the United States.  It is one of 28 member institutions of the Association of Jesuit Colleges and Universities.  The university is accredited by the North Central Association of Colleges and Secondary Schools.  SLU's athletic teams compete in NCAA's Division I and are a member of the Atlantic 10 Conference.  It has an enrollment of 13,505 students, including 8,687 undergraduate students and 4,818 graduate students that represents all 50 states and more than 70 foreign countries.  Its average class size is 23.8 and the student-faculty ratio is 12:1.
Answer: Saint Louis University