There were regiments that historically had ties to some part of the country.But I doubt that there ever was a unit drawn soley from the Bronx. Men could be assigned to whatever unit needed them in WWI. We were only at war for 18 months so every element of deploying an army was done very quickly. I had an uncle who lived in Cleveland, Ohio. Ohio was home to it's own National Guard division. But this man served with the "Bloody Bucket", the 28th Division, Pennsylvania National Guard. He was a draftee and went where they told him to go. Your best bet is to find a document.