Union loyalists were very strong in the southern mountain areas. East Tennessee was a huge Union/loyalist concentration, although it did have pockets of secessionists. Many other Tennessee citizens were loyal to the Union until Lincoln asked for volunteers to fight the rebellion.
Rural West Tennessee had some pockets of very strong Unionist support in the pre-Sumter election.
Tennessee provided quite a few regiments to the US Army to fight against the insurrection.
After Grant took most of Tennessee, the southern economy was in shambles. They significantly depended on Tennessee pork for their protein. ( Texas beef production greatly expanded after the war. Before the war, Oxen were grown as draft animals.) To compensate for that, the pretended confederacy ordered that instead of cash crops like cotton, even large plantations were to raise poultry to replace the missing pork.
To some extent they were successful, but that meant that US Army forces could live off the land, eating the chicken and geese that were locally grown. A visiting congressman brought fattened geese to have cooked for a dinner with men from his constituency. The men were rather embarrassed, they had eaten virtually nothing but geese as they maneuvered behind Vicksburg. After the insurrection forces at Vicksburg were bottled up, Grant was able to reopen the supply lines, and the men were issued hard tack biscuits to supplement their fowl provisions.