Fellow WBTS blogger Robert Moore and others have recently focused on "Southern Unionists" - Southerners who were opposed to secession; which is an interesting topic. Jack Hinson was one of those Southerners, at least initially. But the CW blogosphere is "light" on the Southern Unionists' counterpart: Northern Secessionists.
I just received a copy of William Wright's The Secession Movement in the Middle Atlantic States and will be posting some thoughts on the subject and this book in the future. Though the work is dated, it appears, at first glance, to be a good source on the subject. States discussed are: Maryland, Delaware, New Jersey, Pennsylvania, and New York.