Indiana Code Title 3. Elections § 3-8-2-6

Sec. 6. (a) A declaration of candidacy for:

shall be filed in the office of the county election board located in the county seat.

(b) Whenever the election district for a local office includes more than one (1) county, the declaration of candidacy shall be filed in the office of the county election board located in the county seat of the county that contains the greatest percentage of population of the election district.

(c) This subsection applies to a county having a population of more than four hundred thousand (400,000) and less than seven hundred thousand (700,000).  The chief deputy of the combined election board and board of registration shall post for public inspection a copy of each declaration of candidacy filed under this section on the day the declaration is filed.

(d) This subsection applies if an election district for a local office is located in more than one (1) county.  The circuit court clerk of the county having the greatest percentage of population of the election district shall promptly certify the names of each of the candidates that have filed a declaration of candidacy to be a candidate for the office in the election district to the county election board of each other county in which the election district is located.