GREAT LINK! Thanks!

They did miss one point on the soft surface trails, MESSY for bikes.

To the cost, I understand small towns or rural areas that do not pave trails for the cost and likely lower usage making it hard to justify.

Here's some interesting (well, you'll be the judge of that) details about my area and our rails-to-trails conversions. I live about 15 miles West of Minneapolis. The city frequently makes it high in the ranking of bike cities. We have some amazing bike infrastructure, I use the following trails with varied frequency:

Cedar Lake Trail - Wikipedia, the free encyclopedia - paved super highway for bikes.
Midtown Greenway - Wikipedia, the free encyclopedia - paved
Southwest LRT Trail - Wikipedia, the free encyclopedia (this is the one I use a couple times a week on my commute) This is paved closest to the city and limestone in the 'burbs. And is called the River Bluffs trail for the Western end of the trail.
Dakota Rail Regional Trail - Wikipedia, the free encyclopedia - paved
The Luce Line - limestone and paved closed to the city
Lake Minnetonka LRT - all limestone

All of these trails are part of Three Rivers Park District (it includes multiple counties and cities). The funny thing from my perspective, The Dakota Trail is fully paved and the least useful to commuters - it is mostly a recreational trail. The neighboring county (not in Three Rivers) paved their section of the Dakota Trail to attract more people (seems to be working). But Three Rivers is not willing to pave the trails that commuters are using in the suburbs.

One additional point about living in Minneapolis with limestone, spring melt. When limestone thaws it turns to peanut butter, this is a very good description of the surface (soft) and the color. It is darn near impossible to ride a limestone surface during the spring thaw, and this condition will last until the ground is thawed enough to allow drainage, which is typically 3 to 4 weeks. At least once every spring, I need to make the bone-headed mistake of thinking 'the limestone should be good today' - WRONG!