[1] The premise was that individuals who were frustrated with poor labor conditions and lack of freedoms in urban areas in the East could escape to the frontier, which in turn created a restraint on political repression and labor abuse in the East.
Given the concentration of immigrants (and population) on the Eastern coast, it was hypothesized that making free land available in the West would relieve the pressure for employment in the East.
By analogy with steam pressure (= the need for work), the enactment of a free land law, it was believed, would act as a safety valve.
This theory meant that if the East started filling up with immigrants, they could always go West until they reached a point where they could not move any further.
There is a dispute whether and to what extent the Homestead Act did or did not succeed as a safety valve in ameliorating the problem of unemployment in the East.