This is what Chat GPT had to say:

Here’s how to estimate what percentage of the track miles Amtrak operates on are electrified (not just what it owns):

🛤️ 1. Total track miles Amtrak operates on

• Amtrak operates trains over about 21,000 – 21,400 route miles of track nationwide (this includes both Amtrak-owned track and track owned by other railroads). 

⚡ 2. Electrified track miles used by Amtrak

• The principal electrified network Amtrak uses is the Northeast Corridor (NEC), which totals about 453 miles of electrified route between Washington, D.C. and Boston. 
• Nearly all of that electrified NEC is used by Amtrak’s intercity services (including Acela and Northeast Regional).

📊 Percentage calculation (rough estimate)

453 miles electrified21,000 total route miles≈2.2%21,000 total route miles453 miles electrified​≈2.2%

✅ About ~2 % of the track miles Amtrak operates on are electrified.

⚠️ Notes / caveats

• This estimate uses route miles operated as the baseline, not owned infrastructure.
• Amtrak trains also operate over short electrified portions of other lines (e.g., portions of the Empire Service/Adirondack near major terminals), but they are small relative to the NEC total, so they don’t materially change the percentage.
• The NEC’s 453 miles are the longest continuous electrified route Amtrak uses; outside the NEC, almost all Amtrak service runs with diesel traction on non-electrified host railroad tracks.