Michigan Compiled Laws, Chapter 600. Revised Judicature Act of 1961 § 600.8135

(a) The first division consists of the cities of Saginaw and Zilwaukee and the townships of Zilwaukee, Buena Vista, Carrollton, and Bridgeport, and has 3 judges.However, the first division has 2 judges beginning on the date on which a vacancy occurs in the office of district judge in the first division unless the vacancy occurs after the vacating judge has been defeated in a primary or general election, or the beginning date of the term for which an incumbent district judge in the first division no longer seeks election or reelection to that office, whichever is earlier.

(b) The second division consists of the county of Saginaw, except the cities of Saginaw and Zilwaukee and the townships of Zilwaukee, Buena Vista, Carrollton, and Bridgeport, and has 2 judges.However, the second division has 3 judges beginning on the date on which a vacancy occurs in the office of district judge in the first division, unless the vacancy occurs after the vacating judge has been defeated in a primary or general election, or the beginning date of the term for which an incumbent district judge in the first division no longer seeks election or reelection to that office, whichever is earlier. The judgeship transferred from the first division to the second division is not considered an additional judgeship for purposes of section 8175  1 and may be filled by appointment by the governor if it is the result of a vacancy in the first division.