How to speed up US passenger rail, without bullet trains

Summary

High-speed trains, zooming across the landscape at over 200 miles per hour, have long been a Holy Grail for US transportation advocates. Though projects are advancing in California, Nevada and Texas, progress has been arduous. Even in sparsely populated corners of the American West, from-scratch high-speed rail development is expensive, complex and politically fraught. But brand-new bullet trains are not the only way to deliver faster passenger rail service. In regions with lots of older rail infrastructure, like the Northeast and Midwest, the existing tracks are full of untapped potential.