Question: Where are the roots of the half mile run from?
About the article "Track and field", section "Middle distance".

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Tributaries are listed in order from the source of Four Mile Run to its mouth. 
Middle-distance running events are track races longer than sprints, up to 3000 metres.
The standard middle distances are the 800 metres, 1500 metres and mile run, although the 3000 metres may also be classified as a middle-distance event.
The 880 yard run, or half mile, was the forebear to the 800 m distance and it has its roots in competitions in the United Kingdom in the 1830s.
The 1500 m came about as a result of running three laps of a 500 m track, which was commonplace in continental Europe in the 20th century. 
Middle distance running events are track races longer than sprints up to 3000 metres.
The standard middle distances are the 800 metres, 1500 metres and mile run, although the 3000 metres may also be classified as a middle distance event.
The 880 yard run, or half mile, was the forebear to the 800 m distance and it has its roots in competitions in the United Kingdom in the 1830s.
The 1500 m came about as a result of running three laps of a 500 m track, which was commonplace in continental Europe in the 1900s. 
From its origin, the North Branch skirts the northern edge of the world-renowned Pine Valley Golf Club and enters Lekau Lake a mile down.
A teardrop-shaped impoundment about third of a mile (0.5 km) long, Lekau Lake lies at an elevation of in a hollow of the hills.
Leaving the lake, the North Branch twines its way a mile northwest, down to , and enters Clementon Lake in Clementon, long a recreational mecca for the region.
A quarter mile (0.4 km) below the lake Trout Run enters from the east, and a half mile farther on, Gravelly Run.
The North Branch then runs more to the west for a mile to Laurel Lake, a sinuous half-mile-long (0.8 km) impoundment which lies at an elevation of about .
The North Branch continues its westerly course for three-quarters of a mile (1.2 km) below Laurel Lake, turning northward where Mason Run enters from the south.
It turns to the westward again after another three-quarters of a mile, immediately after which it receives Signey Run from the north.
The North Branch then tends northwestward, widening and slowing a mile along, and, turning west upon receiving Otter Branch from the north a half mile farther down, enters an impoundment at Chews Landing.
This impoundment is a consequence of the constriction at the point about a third of a mile (0.5 km) down where the North Branch passes under the Black Horse Pike.
The North Branch is now tidal and runs westward through wetlands another mile to its confluence with the South Branch. 
Baranof Warm Springs is located on Warm Springs Bay which is just off of Chatham Strait.
Just about a half mile up from the settlement is Baranof Lake, a large glacially-fed freshwater lake.
Baranof Lake is fed from small unnamed glacial run-off streams as well as the relatively large Baranof River.
Between the half mile outlet between Baranof Lake and Warm Springs Bay there are a series of rapids and waterfalls that have proven to be lethal when run.
Baranof Warm Springs is located on the southern part of a 34-mile long, 5 to 10 mile wide exposure of a biotite-quartz diorite batholith that crosses northern Baranof Island.