100 Mile House was originally known as Bridge Creek House, named after the creek running through the area. Its origins as a settlement go back to the time when Thomas Miller owned a collection of ramshackle buildings serving the traffic of the gold rushas a resting point for travellers moving between Kamloops and Fort Alexandria, which was 98 miles (158 km) north of 100 Mile House farther along the HBC Brigade Trail. It acquired its current name during the Cariboo Gold Rush where a roadhouse was constructed in 1862 at the 100 Mile mark (100 miles (160 km)) up the Old Cariboo Road from Lillooet.
In 1930, Lord Martin Cecil left England to come to 100 Mile House and manage the estate owned by his father, the 5th Marquess of Exeter. The estate's train stop on the Pacific Great Eastern (now CNR) railway is to the west of town and called Exeter. The town, which at the time consisted of the roadhouse, a general store, a post office, telegraph office and a power plant, had a population of 12. The original road house burned down in 1937
