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Serum run to Nome reaches Alaska

On this day · 2 February 1925
40 sec read

Twenty mushers and 150 dogs ran antitoxin across frozen Alaska in a relay against a diphtheria outbreak.

Verified · Balto and Togo during the cold winter of Alaska (1925)

On February 2, 1925, a dog-sled relay reached the icebound town of Nome, Alaska, carrying diphtheria antitoxin to halt a deadly outbreak among its children. The serum sat 674 miles away in Nenana, and winter had cut Nome off from ships and planes alike.

The answer was speed by paw. Roughly 20 mushers and about 150 sled dogs ran the serum in a relay across the wilderness, battling temperatures near 50 below and blinding blizzards. The journey took under six days.

Musher Gunnar Kaasen and his lead dog Balto drove the final leg into Nome in the dark before dawn.

Not a single vial broke. The run made Balto famous and is widely credited as inspiration for the modern Iditarod sled-dog race, which follows much of the same historic trail.

674 mi
relay distance
20
mushers
−50°F
cold

Sources & references

2 references

Well-established. Corroborated by 2 independent sources.

1 Balto and Togo during the cold winter of Alaska (1925) peer-reviewed journal (PubMed Central) “From January 27 to February 2, the teams covered 674 miles (1085 kilometers) bringing DAT units from Nenana to Nome.” nih.gov ↗
2 100 Years After the Great Serum Run, Balto's Legacy Endures natural history museum “Balto and his team completed the 53-mile trip to arrive in Nome in the early morning of February 2, 1925—delivering the serum and saving countless lives.” cmnh.org ↗
✓ Last reviewed Jun 7, 2026

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