The same reason that most other countries don't have them. They're very expensive to build per mile of track and there's no viable route for them that can't be done more cheaply with conventional rail or monorail.

The United States lacks a maglev (magnetic levitation) network primarily due to exorbitant infrastructure costs, political gridlock, and land rights issues. Unlike traditional high-speed rail, maglev requires entirely new, purpose-built tracks that cannot share the existing freight-dominated rail network. The cost to implement high-speed rail in the U.S. is estimated at over $4 trillion, with maglev being even more expensive due to its specialized technology. Furthermore, the "Super MagLev" project proposed between Baltimore and Washington, D.C., was recently stalled in late 2025/early 2026 due to poor planning and rising costs (estimated at $10–$20 billion for just 40 miles). Heavy opposition from community members whose homes lie in the path of new tracks and the dominance of the automotive and aviation industries have also hampered federal investment. While countries like Japan and China have government-prioritized transit, the U.S. rail system is largely owned by private freight companies, meaning any new high-speed passenger project faces massive legal and financial hurdles to secure a dedicated right-of-way.