You can thank Earl Warren for that. Reynolds v. Sims essentially disenfranchised everyone not living in a big city.
Reynolds v. Sims - Wikipedia
From the link:
Reynolds v. Sims, 377 U.S. 533 (1964), was a landmark United States Supreme Court case in which the Court ruled that the electoral districts of state legislative chambers must be roughly equal in population. Along with Baker v. Carr (1962) and Wesberry v. Sanders (1964), it was part of a series of Warren Court cases that applied the principle of "one person, one vote" to U.S. legislative bodies.
Prior to the case, numerous state legislative chambers had districts containing unequal populations; for example, in the Nevada Senate, the smallest district had 568 people, while the largest had approximately 127,000 people....
Seems reasonable to me...