In Solow's growth model the growth rate of the output or GDP of a country is denoted by $g$. In the model this can be decomposed to $$ g = g_l + g_k, $$ where $g_l$ is the growth rate of the effective labor force and $g_k$ the growth rate of capital. If you calculate the growth rate of per capita GDP population growth will not play a role. (Per capita growth is 'kind of' like $g_k$, but not quite, as technological advancements are factored into the growth rate of effective labor.)
Does historical data support the statement that the effect of population growth on per capita GDP growth is zero?
I did some limited searching and it seems that while US growth is sometimes set as an example to other western countries, the real difference is in population growth, not per capita GDP growth.
Am I being too superficial in my examination? Are there more subtle effects, such as a lagged effect due to the pension and elderly care systems?