landesweit
nationwide / statewide
Valid, widespread, or taking place throughout an entire country or federal state.
Die neuen Corona-Regeln gelten ab morgen landesweit.
The new COVID rules apply nationwide starting tomorrow.

nationwide
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nationwide / statewide
Valid, widespread, or taking place throughout an entire country or federal state.
Die neuen Corona-Regeln gelten ab morgen landesweit.
The new COVID rules apply nationwide starting tomorrow.

The word is made up of 'Land' (country/state), the linking element '-es-', and 'weit' (wide/far). It literally means 'as far as the country/state extends' and therefore describes a geographic extent.
Die Hitzewelle betrifft das Land landesweit.
The heat wave is affecting the entire country nationwide.
The ending '-weit' is very productive and can be combined with many geographic terms to describe their area of application. Examples are 'europaweit' (Europe-wide), 'weltweit' (worldwide), or 'bundesweit' (nationwide/federal).
Das Produkt ist mittlerweile weltweit bekannt.
The product is now known worldwide.
'Landesweit' can be used as an adverb or as an adjective. As an adverb, it often appears at the beginning of a sentence for emphasis; as an adjective, it stands before a noun and is declined.
Landesweit kam es zu Stromausfällen.
There were power outages nationwide.
The 'Land' in 'landesweit' can refer to an entire country (e.g., Germany) or to a federal state (e.g., Bavaria). The exact context makes clear which geographic area is meant.
Die Bundestagswahl findet landesweit in ganz Deutschland statt.
The federal election takes place nationwide throughout Germany.
national
'national' and 'landesweit' can both mean that something affects an entire country. 'national' is an adjective and often describes things that belong to the nation or are important for the whole country, for example 'nationale Politik' (national politics/policy). 'landesweit' is usually an adverb and says that something applies, is known, or takes place throughout the whole country. In some contexts, 'landesweit' can also refer to a federal state if it is clear which country or state is meant. Learners may confuse the words because both refer to more than just a small region. In practice: 'national' describes the connection to the nation, while 'landesweit' describes the spread across the whole area.

Der neue Fahrplan gilt ab Montag landesweit.
The new timetable applies nationwide starting Monday.
Das nationale Museum zeigt Kunst aus verschiedenen Teilen des Landes.
The national museum shows art from different parts of the country.