I'm incredibly blessed with an overabundance of hiking trails within 4-5 minutes of my house. I can walk out my front door and get in a 4 mile hike with 300 feet of elevation gain without leaving my neighborhood. A few minutes drive from my house is a trail that climbs 2600 feet in 2 miles that I use to train for my Grand Canyon trips.
On the flip side, what is the furthest distance in the U.S. that someone needs to drive to find a decent hiking trail that will give you at least 250 feet of vertical gain? Have a friend that lives in a town in Michigan that is pancake flat but he is still able to find hills to train on within 45-60 minutes of his house. Stuff like sledding hills, trails on the sand dunes along Lake Michigan, etc.... Off the top of my head I'd guess places in Texas or Florida would be difficult to find a decent trail to hike.
Added Edit: To be more clear I meant 250 feet of accumulated elevation gain. So an easy hike with rolling hills would cover this. Not 250 feet of gain in a single hill. More curious to see how far some people would have to drive to find a hill.