I answered a related question about the the initial construction and control of the canal here, based on Maurer and Yu, The Big Ditch, and their earlier article, "What T. R. Took." Their broad conclusion is that the canal had very little spillover effect for Panama (at least in the period covered by this subreddit; the handover of control was 1999), and that the vast majority of the benefit accrued to the US in one form or another.