How did the Portland Trailblazers get their name?

It was determined by a contest in 1970 with over 10,000 entries. The name is derived from the rugged character of the region and the role of the Oregon Trail in US history.

There were 172 people who sent in the name ‘Trail Blazers’,” Glickman said ... The nickname was unique in professional sports at the time. No other major professional or university sports teams were using either the Blazers or Trail Blazers in 1970. The name, as Glickman noted at the time, “reflects both the ruggedness of the Pacific Northwest and the start of a major league era in our state.” Trail Blazers (or, more properly trailblazers) is defined by Webster as “One that blazes a trail to guide others: A pathfinder: A pioneer.” The actual name came from a practice by explorers making paths through forests and marking the paths by chopping white “blazes” in trees’ bark so others could follow. The term “trailblazing” is associated today with those on the cutting edge of discovery in such areas as space exploration, science, medicine and technology.

nba.com/blazers/pemco/how-blazers-got-name webpage no longer exists
https://www.nba.com/resources/static/team/v2/blazers/pdf/2020-21_BlazersMediaGuide.pdf

This is just conjecture because I couldn't find the answer on their official site or Wikipedia or by a simple google search.

I'd guess it has to do with the Oregon Trail that went from Missouri to Oregon on which pioneers would travel out west in 19th century United States. Pioneers would "blaze" the Oregon Trail heading west towards Oregon ending at a destination very close to modern Portland.

https://en.wikipedia.org/wiki/Oregon_Trail