Why The?

[L Austin France]

French departments talked about here & other similar places often have their names preceded with 'The' for example The Var & The Lot, from memory, yet others such as Finistere never seem to be mentioned in this way.
Why is this?

[MAD87]

Maybe it's to do with rivers that run through those départements? We are la Haute-Vienne, next to la Creuse, la Corrèze and La Charente. It's the only thing I can think of.

[exile]

Just the way we translate from French.

In French they all always have "the" at the start. The same is true of town and city names where in English they are almost universally ignored but with the odd exception - for example Le Mans. This always throws me in French when speaking of from Le Mans - which of course is du Mans.

[Chappers51]

We’re Le Pizou and it took me several years before I realised I had to use du Pizou on occasions.(slow learner!)