Ryan Donahue of the Trust for Public Land says that it depends on age, health, time availability, quality of surroundings, safety, climate, and many other factors.
One problem with assessing how far people will walk to use a park is that most walkability studies are focused on commuters rather than park users who have a mix of motivations. However, it does seem that the quarter-mile standard used to assess the walkability of transit stations is mostly applicable to parks as well:
"...research supports the validity of both quarter-mile and half-mile distance goals, depending on perceptions of the built environment, safety, and time constraints. Of course, people's preferences and habits are only part of the equation for planners, who must also take into account the cost effectiveness of expanding the park system versus improving current parks or focusing on connectivity."
FULL STORY: Pedestrians and Park Planning: How Far Will People Walk?

Florida Considers Legalizing ADUs
Current state law allows — but doesn’t require — cities to permit accessory dwelling units in single-family residential neighborhoods.

HUD Announces Plan to Build Housing on Public Lands
The agency will identify federally owned parcels appropriate for housing development and streamline the regulatory process to lease or transfer land to housing authorities and nonprofit developers.

Has President Trump Met His Match?
Doug Ford, the no-nonsense premier of Canada's most populous province, Ontario, is taking on Trump where it hurts — making American energy more expensive.

OKC Approves 7.2 Miles of New Bike Lanes
The city council is implementing its BikeWalkOKC plan, which recommends new bike lanes on key east-west corridors.

Preserving Houston’s ‘Naturally Occurring Affordable Housing’
Unsubsidized, low-cost rental housing is a significant source of affordable housing for Houston households, but the supply is declining as units fall into disrepair or are redeveloped into more expensive units.

The Most Popular Tree on Google?
Meet Rodney: the Toronto tree getting rave reviews.
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