It may also mark a seminal day in the tortured history of Anglo-Irish relations.
Ironically, the crowning achievement of Mr Manning's career may also mark its sunset.
The latest abductions may also mark the sad resurgence of the use of child soldiers.
Such changes may also mark the import of American-style "culture wars" into Mexico and Latin America.
But Jack and Jill may also mark something more significant: the moment when cinematic cross-dressing officially stops being funny.
Ichiro Suzuki's achievement has added excitement to America's pastime, but it may also mark a turning point for our own.
So ends Blackmon's golf career; it may also mark the last time anyone hits the links with Crossman, lest they get a Rube Goldberg octopus scouting report.
The state may also mark the end of John McCain's presidential hopes or, just possibly, the start of a revival.On the Democratic side, the analysis is different.
It may also mark the start of a political degeneration that sees the country slide towards nationalism, autocracy or something nastier.
