This may work. Suppose A is the top block and B is the bottom block.
Now, create A block with the exposed filter district. Next, create the B block with the two exposed filters for district and Census. Make sure the identifier in the B block for the district exposed filter should be same as on A block. So whatever value you applied in A block will also filter the result of the B block with the same filter criteria. Show both on a page by assigning them in a region from here in admin /admin/structure/block
. Now, you can hide the district field of the B block using the CSS.
You can also look at the Views Field Views module to help you to achieve the same with other way.