The map below shows a stable population for Lincoln County over the past half-century.

As with all data, timing is everything. The 1970 Census documented the boom that accompanied the Libby Dam, the railroad and highway relocation and the tunnel:
Year Population
1940 7,882
1950 8,672
1960 12,537
1970 18,063
As the map shows, the county population has been fairly stable over the past 50 years – it’s one of those spots where the numeric data doesn’t give the whole picture. That 44 percent population increase between 1960 and 1970 wasn’t just people moving in – that decade also includes the loss of the Kootenai valley from Libby Dam to the 49th parallel.
Another aspect is that the new housing for the boom was built quickly – and the quickest way to get more housing was to develop water and sewer connections and bring in trailers – mobile homes was the nice term back then.
Until 1954, laws limited trailer width to 8 feet on the highways – and that meant that when the influx started in the mid-sixties, the used trailer market offerings were dominated by 8-wides. Sure, Walsh-Groves purchased new 12-wides and moved them in for their cadre – but individual laborers generally picked up a second-hand 8-wide and moved to Lincoln County. This photo reminds me of an elderly couple (probably both far younger than I am now) who moved in 3 trailers set up as a rooming house . . . one was the first 2-story trailer I ever saw. Pat and Nora, their names were.

Simply put, the housing that came in for the boom that showed up in the 1970 Census wasn’t always the sort of housing that lasted. An unanticipated consequence of building trailer courts to provide affordable housing was trailer abandonment. At the time, it was fairly cheap to buy a used trailer and move it in – and more costly to move it out after 3 or 4 years.. It kind of left the trailer court owner with an unplanned labor demand. When you couldn’t sell – or even give away – an old trailer, the option was a little diesel, a match, and bury the frame.
One of those old trailer frames is buried in my hay field. Another – from when the Trego post office expanded due to the influx of population – serves as the bridge across the channel between the ponds. That 0 to 0.5% growth includes housing that came in old and was abandoned as workers headed to the next construction boom. (I think that was the Alaska Pipeline, and those old 8-wides would never have made that trip on the Al-Can.)
Most of the construction boom was in Libby – and the immigrant population after 1970 was different. Those new residents were looking to own homes – and as the trailer pads diminished, so did the readily subdivided parcels of land. More recently the population growth has been occurring in the North part of the county than around Libby, as well as the tax base increasing more rapidly.