Trump’s Funding Threats Build a Case for Private High-Speed Rail

California has helped create much of the technology powering the 21st century. But travel between Los Angeles and San Francisco by train still feels trapped in the past.

Now, the state’s plan to modernize that corridor — a long-promised high-speed rail line — is facing its most serious threat yet. President Donald Trump has called the project “stupid” and vowed to block $4 billion in federal funds, escalating a broader push by his administration to withdraw support from mass transit initiatives across the country. “This government is not going to pay,” he said earlier this month.

The threat lands ...