I would like to know if some of the former New Haven Railroad is now part of CSX. I know that CSX bought 42% of the former Conrail system including New York Central several years ago. CSX is one of my favorite railroads since I live near a CSX mainline in Georgia.
Technically speaking on a business level. No.
However, CSX does go over former NHRR trackage around New Haven to New York on the NH line.
CSX also operates in Mass on the NEC that was NHRR’s Shoreline.
I believe CSX operates on most of the remaining NH lines in Massachusetts including the Old Colony Lines and the old New York & New England Lines.
I believe answer is yes to your question. NS does not operate on any former NH tracks. CSX got any former NH lines by default as a result of it getting the former-NYC Boston & Albany Line to Boston as part of the merger deal.
The answer is yes, CSX does own some of the New Haven.
They have several miles around New York City, and several more miles north from New Haven in CT.
In Mass, they own lines from Fitchburg down through Mansfield, and Attleboro to Fall River, New Bedford and Braintree.
Note that Amtrak owns most of the former shoreline(now the NEC). Providence & Worcester RR operates freight service on the line from RI south through Connecticut. CSX is still the freight operator from Boston to the RI/Mass border. P&W itself owns a good chunk of ex NH trackage in RI, Mass & Ct, including the “historic” Providence & Worcester main from Pawtucket, RI to Worcester.
The “historic” P&W main was always (!) owned by P&W, which always existed in a corporate sense since the line was built. It’s only that prior to about 1970 or so, P&W leased its lines to NH and then PC. The lease was then terminated and P&W resumed independent operations.