Why did northerners in congress accept california's application for statehood while southerners rejected it

The issue was slavery.

California was expected to be admitted as a free state.

The South knew that with enough more free states, the free states could get an amendment passed to outlaw slavery and so they wanted to prevent that possibility by keeping the number of free and slave states as equal as possible.

Not a question but you !

Where’s the map ? ? post it