What's the largest territory where all power within the jurisdiction belongs to a single elected official?

Question

I'm looking for the largest territory (by population) which satisfies the following criteria:

1. A single person has all the decision making power in their hands, constrained only by whatever powers are delegated to said territory from a higher level of government. I.e. a mayor of a city that doesn't have a city council or where the mayor can completely ignore the city council if they so desire.
2. Said person is elected democratically (directly or indirectly) in an election where the majority of the territory's residents can participate. So positions such as Saudi Arabia's King are excluded.
3. The powers of said person can be executed de facto, not de jure. So the British Queen wouldn't count even if it was an elected position, as she doesn't exercise any of her powers directly these days.
4. If no such notable positions exist these days, historical positions from within the past 100 years would count too.

Largest example that I'm aware of is Bartow County, Georgia, with a population of 107,738:

It has a sole commissioner government, and is the largest county by population of the few remaining in Georgia with a sole commissioner.

Answer 1

While not directly elected, historically, local governments in France were governed by legislatively elected prefects in turn chosen by elected legislators, who held power similar to that a sole commissioner in a Georgia county with that system had.

As another example, in many jurisdictions, the district attorney, or sheriff, or other elected executive branch official, does not directly report to any other elected official and may have statutory budget protections.

For example, in Colorado, district attorneys are elected from multi-county judicial districts and are not accountable to any other elected officials except for funding which the funding agencies are required by law to provide at an "adequate" level. They don't report directly to either the state attorney general (as DAs in Florida do) or to county commissioners or sheriffs. But, of course, most of their actions must be ratified by judges and juries to have real effect.

Similarly, in Colorado, the Secretary of State, a statewide partisan elected official, isn't subordinate to the Governor and because the office's functions are predominantly funded via user's fees, isn't very accountable through the power of the purse, to the legislature either. Then again, the subject-matter of which this unilateral power is held is require limited.

In a lot of ways, the Prime Minister in a country that is unitary rather than federal, with a Westminster style parliamentary system with only one truly powerful legislative house, de facto, comes quite close to the "elected King" model. The Prime Minister of the U.K. isn't so far from this model, for example, at least in England proper. Yes, there are parliamentary votes, but once a P.M. is chosen, party discipline is such that the P.M.'s decision holds on any issue that the P.M. declares is not a "free vote" until an election is held or there is a defection in his party that causes him or her to lose the confidence of parliament.