I edited my comment to New York. Considering that "Ontari" is named after the Canadian province of Ontario, which borders New York and Nia is named after Niagra Falls a city and landmark in both New York and Ontario.
To be fair, it was stated that Azgeda stretches for a 1000 miles and with names like Atohl (Massachusetts) Ontari (Ontiro) Nia (New Youk), this shows how vast Azgeda is and an argument can be made for Detroit too. On the map that was used in season 3, Azgeda borders Trikru/Mount Weather at the north west, which is the direction you would need to go in order to get to Detroit. I could be wrong as JR named Madi after Madison Wisconsin, the university he attended at, which is nowhere near Shallow Valley and Detroit is where he was born.