NA? North America? Native American (Indians)? Initials for some famous person? Or group? National Association (of something)?
New Amsterdam became New York much earlier. Maybe they called it NA, like they call it NY today?
New Arrivals, (immigrants)? New aliens? who lived throughout the East & West, or North & South? Many Germans (Hessians) fought for the Union Army. they used to call Prussia an army in search of a country. They contracted out everywhere, many for the British in the 1776 war, but also for the Union in the Civil War. Pay them and they come. Soldiers of Fortune. They were throughout the country as the battles took them.