Mason Dixon is northern border, nuff said. Only reason Md wasn't confederate was all the politicians in DC in the way, LOL. I'm near BelAir Md (north of Ball-mer) There's historical markers all up and down the road with references to Union AND Confederate officers. Besides my mom was from Georgia.
You know the story here, right?
When Maryland was threatening to secede, Lincoln ensured troops were stationed in Rockville, Annapolis and other sites, totaling >20,000. A new push for secession was to be addressed by the MD General Assembly, which had been trying to remain neutral, with interests on both sides. The session was set to open in the temporarily anointed state capital of Frederick, after previously voting both not to secede, and not to allow Union troops to use its rail lines. On Sept 17, 1861, just as the Assembly was to convene, the President ordered the Conferedate sympathizing leaders arrested and held at Ft. McHenry. The secession effort died for lack of a quorum, the capital was moved back to Annapolis, and the state government tilted to support Federal war efforts. Maryland remained an unenthusiastic Union partner, but despite (or because) 40% of its population was slaves, emancipated them and abolished slavery before the war ended.