"Across the nation" can be substituted with various synonyms depending on the context, purpose and the tone of the message. Words like "nationwide", "throughout the country", "coast-to-coast", and "internationally" can be used to convey the same meaning. "Nationwide" suggests coverage or reach that spreads to every region or state within a country. "Throughout the country" means from one end of the country to another. "Coast-to-coast" implies covering the distance from one end of a country to the other. "Internationally" describes expansion beyond national borders. These synonyms provide a range of language options, enabling writers to communicate in a way that is more precise, impactful, and effective.