Chinese with US Passport applying for visa to China

I have been an US citizen since year 2001. I was born in Macau and lived in Macau until 1989. The last time I visited the Mainland China was in July 1990. I believe that I used the travel document specially for Macau residents to enter China at that time. However, I no longer have that document with me. I was a Portuguese citizen at that time.

Should I apply for a Chinese Visa as an US citizen, or should I apply for a travel document as a former Macao Resident? Since I lost the previous travel document to China, what should I provide to the Chinese Consulate when I apply?