I am currently searching for information about my Greatgrandfather Michael Dillon. He left ireland and came to the United States sometime in the 1860's. He settled in Chicago, Illinois, where he married a Margaret Hart also from Ireland about 1867. He had 9 children and died in 1900. One of his son's death certificate gives Galway as the county his father was from and Mayo as the county his mother was from. I believe he may have had a brother named Patrick. Any information about Dillon's would be greatly appreciated.
Could you please post your message here: http://www.irelandxo.com/group/county-mayo
It is very difficult to carry out research without an exact place of origin or more specific dates. Do you have any other documentation in your family, such as family bibles or other official documents? These may give more clues. You should consider asking other relatives for information. Someone else might know the vital clue that you need to get you started.
I can suggest some websites you could look at, but really you will need more details before you can really get started.
Civil registration records are available from the General Register Office (GRO). These start from 1864 however. You can access the website here: http://www.groireland.ie/research.htm
Have you tried checking the Ellis Island records (www.ellisisland.org) or the Castle Garden records (www.castlegarden.org)? Generally, more information was given at the port of arrival rather than the port of departure. If you knew which city they arrived at, this could be a good place to find more information, and perhaps even find out an exact place of origin.
You could also try checking the land records called the Tithe Applotment Books (1823-38) or the later Griffth's Valuation (1848-64). Griffith's is freely available here: www.askaboutireland.com or here: www.failteromhat.com Failte Romhat has lots of other useful links you could try looking at.
You could also take a look at the 1901/1911 census records to check for the frequency of the surnames in those counties. It might help to give you some leads perhaps. You can check this here: http://www.census.nationalarchives.ie/search/
Please make sure you link anyone else in your family who is interested in their Irish heritage to our site - and indeed anyone else you know of Irish heritage.
Genealogist (Ireland XO)
You might want to reach out to find other descendents of Michael and Margaret using the genealogy Surname Message Boards. I've had good luck on Ancestry.com and have found cousins living nearby with family letters and pictures. You don't have to be a paying member to use the Message Boards, but you do need to sign in.
I'm also from the Chicago area. The Chicago Tribune Obituaries Archive is a good source for tracing the families and finding married names of the daughters. I have online access if you need some help. Happy to do lookups for you.
Also I recently found that Family Search has scanned early birth and marriage records for Chicago parishes. It's a bit tedious, but you might find some other family names as sponsors. https://familysearch.org/search/image/index#uri=https%3A//familysearch.o...
If you use Facebook, there are some very helpful County Genealogy Groups. You might also find other Dillon/Hart researchers.
Ireland Reaching Out
Michael Cusack House
25 Dunkelin Street