The Arab-American Collection at the Smithsonian is a great resource. The collection was begun and nutured by Dr. Alixa Naff. She was haveing funding problems so I do not know if it still exists. Most final census reports can show totals for ethnic groups but people of Middle Eastern background were considered "TURKS" and race was considered "black" so early totals would not reflect a correct total for Arabs. I believe this changed with the 1920 census. Christians at least here would say they are "Assyrian" not Syrian or Lebanese. Many Muslims would also be insulted by putting a label on them of "Turk"