I am looking into the impact of the annexation of Hawaii on sugar prices in the US. I've been searching for days for the above dataset but cannot find it. Would any of you know anything about it?
If you're at a University, you might want to ask your local librarian. They'll be most familiar with the resources available to you at your institution. I'm a business and economics librarian (and sort of known among the other librarians for being good with data questions) so I help students with this kind of question all the time. Even if you're not a student, librarians are usually happy to help and public universities also usually allow some access to their resources if you visit campus. The subject librarians most likely to be able to help are probably government documents librarians, economics/business, or history. A useful thing to know for this kind of price is that sugar is considered a commodity.
Early data like this is hard to find freely online. Even most subscription databases don't often go back that far; you have to know where to look. You'll also run into problems comparing over a long time because the way data has been collected has usually changed over time. One source most university libraries (and some public) should have in some form is the Historical Statistics of the United States. It comes both online and in print (in several editions). I prefer the online version for obvious reasons (you can download!). Each table in the online version also has extensive documentation on the data which will inform you of the different sources they used and give you some guidance on making comparisons across years. The print version might have these as well, but I can't check as I'm not at the library today. There are several tables on sugar in Historical Statistics of the US, including one called Wholesale prices of selected commodities: 1784–1998 which includes sugar. The source of sugar price data changes 4 times before 1890 when it settles into using Bureau of Labor Statistics Data. The main sources they list are Arthur H. Cole, Wholesale Commodity Prices in the United States, 1700–1861, Statistical Supplement (Harvard University Press, 1938); Annual Report of the Director of the Mint to the Secretary of the Treasury for the Fiscal Year Ended June 30, 1881 (U.S. Government Printing Office, 1881); Wholesale Prices, Wages, and Transportation, Senate Report number 1,394, 52d Congress, 2d Session, part 2, 1893.
The bulk of their data after 1890 comes from annual (and then monthly) reports from the Bureau of Labor Statistics called Wholesale Prices and Price Indexes and later the Statistical Abstract of the United States. FRASER from the Federal Reserve Bank of St Louis has these archived but it would be more laborious to use as they're just pdfs.
I wasn't able to find the same sugar prices on the BLS website, but they do have some historical data there. I only found the producer price index which isn't quite the same (although still might be helpful for your analysis) and didn't find it for sugar earlier than the 1970's. You might find more if you look further. This data retrieval guide is helpful. FRED also has some of the same BLS data and is easier to use in some ways.
If your University subscribes to a database called Global Financial Data, they also have US sugar spot prices from 1784-2015. Those prices are also compiled from several different sources. While Global Financial Data does list them, they don't have the rich documentation that Historical Statistics of the US does.
This site will give you sugar prices since 1912, but it does not go back to 1850.
http://www.tradingeconomics.com/commodity/sugar
This source, pages 207-209 has (I think) what you want: