San Francisco has the best parks to be found in the 40 largest U.S. cities, according to data released last week by The Trust for Public Land.


The Trust's new ParkScore park ranking system grades each city by several factors related to its parks: how many people in the city live within a 10-minute walk to a park; the median park size; the percentage of the city devoted to parks; the number of playgrounds per 10,000 residents; and how much money the city invests per capita on those playgrounds. The system also looks at park accessibility for three age demographics — people under 20, over 64, and those in between — and by income levels.


San Francisco ranked extremely high in all of those factors. According to the city's ParkScore ranking, nearly 20 percent of the city is devoted to parks and its median park size is 1.97 acres. The city spends $291.66 per resident on its parks and has 1.78 playgrounds for every 10,000 people. Nearly 100 percent of San Francisco's population across all ages and income levels has parks within walking distance of their homes.


"You can't have a great city without a great park system," Christopher Kay, chief operating officer of the Trust, said in a prepared statement. "Studies show that parks help children and adults get the exercise they need to stay healthy, generate hundreds of millions of dollars in economic activity, and help bring neighbors together."


Sacramento had the second-highest ParkScore, coming in just half a point behind San Francisco. Boston and New York City tied for third place. Washington, DC, came in fifth. Portland, Oregon, ranked sixth.


Fresno had the lowest ranking out of the 40 cities. The California city has a significantly larger median park size than San Francisco — 4.9 acres — but only 2.1 percent of its land is devoted to parks. It has 1.35 playgrounds per 10,000 residents and spends just under $55 per person on its parks. More than 60 percent of Fresno's residents do not have access to parks within walking distance of their homes.


The ParkScore rankings are available online, where users can look at the data for each city, explore maps of the cities' parks, and compare the parks in various cities side-by-side. Urban planners can also use the site to learn how to improve their parks (and therefore their scores).


No city received a perfect ParkScore rating and Kay says "that means every city can improve. A concerted effort to improve local park systems not only means a better ParkScore, but also a healthier, more beautiful, and more vibrant city." She says the Trust is "eager to work with municipal leader and volunteers" to help inspire cities to improve their local parks.