Submitted by Jason Hardrath:

https://trails.lacounty.gov/Trail/265/san-gabriel-river-trail

"This multi-use trail runs north-south, stretching from Azusa to Seal Beach. Though the trail travels through an urban environment, adjacent parks and natural features help diversify the landscape. The San Gabriel Mountains in the distance provide a scenic background for the northern portion of the trail, whereas the ocean serves as a destination point to the south. The trail is a popular bicycle route."

Jason Hardrath submitted this route, which links Mt Shasta (14,162') with the small but significant sub-peak, Shastina (12,330').

Brendan Pytka submitted this clever route:

However you want to run between the two stations!  Here is one possible route: Start at Penn Station in New York City and run north to and across the George Washington Bridge into New Jersey; run south and west to the US 1 / US 9 bridge from Jersey City across Kearny Point to Raymond Boulevard in Newark; run along Raymond Boulevard on the Newark waterfront to Penn Station Newark. If you stick to the waterfront, the distance is over 30 miles, but an inland route could be under.