US Inventions before the US existed? 
What is the rationale for having inventions from before July 4, 1776 in the article? It seems quite odd to me, so am I missing something?   

It is no more less odd than inventions added to the Chinese inventions page before the People's Republic of China came into existence in 1949. Hence, if that were the case, then China can only add inventions to their list from the year 1949 and onwards.

Likewise, prolific inventors such as Bejamin Franklin and Thomas Jefferson were and became American citizens after independence was declared.