- Mechanical Engineer at Dow Chemical in Midland, MI from May 1985 to March 1986
- Project Engineer at John Brown Engineering in Mt Vernon, IN from March 1986 to June of 1988
- Became licensed as a Professional Engineer in 1990
- Member of Indiana Farm Bureau, National Society of Professional Engineers, Jasper Chamber of Commerce, National Federation of Independent Businessman, and Dubois County Builders Association
- Messmer and his two brothers are now co-owners of Messmer Mechanical, Inc. in Jasper.
- Elected to the Indiana House of Representatives in November 2008, re-elected 2010, re-elected 2012
- Co-Chairman of the Economic Development Study Committee 2011, 2012, 2013
- Graduate of Jasper High School in 1981
- Graduated from Purdue University with a Bachelor of Science in Mechanical Engineering in May 1985
- Mark has been married to Kim for 29 years and they have four children, Eric 26, Laura 23, Madeline 19 and Luke 18.
- Mark has been very involved in the activities of his children through coaching their sports teams for over 12 years, as a Cub Scout leader for over 20 years, and helping the Band Parents as a member of the "Pit Crew" for 5 years, and helping with concession sales at football games and at the Strassenfest stand for 10 years.
- Music Minister at his church (Holy Family Catholic Church) since 1993
- Member of his Parish Council from 1990-1993
- President of the Parish Council 1992-1993
- Member of the Finance Council 1988-1991
- Member of the Holy Family School Board 2001-2004
- President of the Holy Family School Board 2003-2004
- Active member in parish's renewal program called Christ Renews His Parish and attended Cursillo in 1992
- Member of the Parish Picnic Committee 2006-2009
- Member of the Capital Campaign Committee for the recent school and church improvements 2002-2007
- In addition, Mark has chaired many other fundraising projects for the church and school.
- Mark has been a member of the Jasper Kiwanis since 1999
- serving as Treasurer 1999-2001
- Vice President 2001-2002
- President 2002-2003
- Secretary 2003-2006
- Mark was recognized as Distinguished New Member in 2000
- Distinguished Secretary for the '05-'06 year
- Indiana Kiwanis Foundation Board Member
- Lincoln Division coordinator for the International Foundation Eliminate MNT project in 2012
- Member of the Knights of Columbus, 3rd Degree
- Member of the Son's of the American Revolution
- Member of the Loyal Order of Moose, Jasper Club
- Member of the Evansville Chapter of the American Society of Heating Refrigeration and Air conditioning Engineers since 1989
- Served as President in 1992-1993.
- Chairman of the Technical, Energy and Government Affairs Committee 1992-2008.