Google Trends interest by region for one keyword: 0-100 interest per subregion of a country (or per country worldwide), past 7 days to 5 years, in one $0.03 GET. Use when you need where a keyword is searched most, for geo-targeting or local market research. A live call takes up to about 30 s. Bad input is free; upstream errors are not charged. Too little Google data gives an empty answer, which is still charged.
https://keywords.duoleads.com/v1/interest-by-region