The fair place to meet is Cleveland, OH — the city closest to the midpoint of Milwaukee and New York. From the farther side that’s about 8 hr 28 min of driving.
Recommended midpoint
Cleveland, OH
From Milwaukee
7 hr 1 min
335 mi to Cleveland
From New York
8 hr 28 min
404 mi to Cleveland
Milwaukee has the shorter trip; the split is off by about 1 hr 27 min. The alternatives below can even it out. Milwaukee and New York are about 732 miles apart.
Milwaukee and New York are about 732 miles apart by road. Split the difference and you arrive near Cleveland, the city closest to the halfway point between them. That puts roughly 7 hr 1 min of driving on the Milwaukee side and 8 hr 28 min on the New York side — the fairest single meeting point among the cities near the middle.
That's a half-day drive from each side, so Cleveland suits an overnight or a weekend rather than a quick coffee — long enough to want a reason to stay, short enough to drive.
If Cleveland doesn't have what you're after, Pittsburgh and Detroit are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Milwaukee and New York.
Cleveland is a city in the U.S. state of Ohio and the county seat of Cuyahoga County. Located along the southern shore of Lake Erie, it is situated across the lake from Ontario, Canada, and is approximately 60 miles west of the Ohio–Pennsylvania state line. Read more →
Milwaukee is the most populous city in the U.S. state of Wisconsin. It is located on the western shore of Lake Michigan at the confluence of the Milwaukee, Menomonee, and Kinnickinnic Rivers. Read more →
New York, often called New York City (NYC), is the most populous city in the United States. It is located at the southern tip of New York State on New York Harbor, one of the world's largest natural harbors. Read more →
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.
Estimates use straight-line distance and typical road speeds; real drive times vary with route and traffic.