Glassman was born on March 24, 1962, in Havre de Grace, Maryland,[4] and grew up on a sheep farm in Level.

[4] At a local level, Glassman is a member of the American Sheep Council, Harford County 4-H Club, the Harford County Farm Bureau, the Level Volunteer Fire Company, and Omicron Delta Kappa National Leadership Society.

[4] On June 7, 2013, Glassman said he would not seek re-election to the Maryland Senate in 2014, instead announcing a run for Harford County executive.

[12] In November 2015, Glassman said he was considering a run for the Republican nomination in the 2016 United States Senate election in Maryland.

[18][19] Following his defeat, Glassman worked as a lobbyist during the 2023 legislative session and started his own lobbying firm, Deer Creek Government Relations, in June 2023.

[21][22] During his first year as county executive, Glassman unveiled a plan to revive development initiatives at the James Run corporate site near I-95, and with establishing an agricultural research and exposition center near Dublin.

[25] In February 2021, Glassman said he supported a bill introduced in the Maryland Senate to create an all-elected school board in Harford County.

[26] In March 2013, Glassman said that he opposed the Firearm Safety Act of 2013, calling the bill "an infringement on the law-abiding folks" and not a deterrent to criminals who use guns.

[35] In August 2021, Glassman said that he had "no objection" to putting the question of legalizing cannabis before voters, but said he'd "wait for pass judgement on the implementation legislation".

[42] Shortly after the events, Glassman announced he would consider a run against Harris in 2022,[43] but he ultimately ran for Comptroller of Maryland in 2022 instead.

[45] Aside from politics, Glassman is a sheep farmer who lives in Darlington, Maryland,[46] and is married to his wife, Dari.