How many hump yards located inside city limits
If your question is "how many hump yard are located with the city limits of a large city" I'd say in general the railroads tried to build hump yards 'out in the country' so they had plenty of room. That being said, in many areas here in the Midwest train yards and facilities that were built in what was then farm country are now inside the city limits, or in what's now a first-tier suburb. BNSF's ex-BN/ex-NP hump at Northtown Yard is maybe 6-7 miles north of downtown Minneapolis, which was probably way out in the stix 100 years ago, but now is surrounded by residental housing and businesses.
Speaking in a purely political sense, I would estimate that almost all of the hump yards in the United States are located, in whole or in part, within some place's, `City limits.'
Of course, the `city' might be a flyspeck on the map, but many such have wide-flung city limits that include a lot of sparsely populated countryside. Especially here in the Far West, there are `cities' with populations measured in three digits which are bigger than some Eastern counties.
Chuck (Who once lived in Ashland City, TN - which would vanish without a trace if dropped into the LA basin)