Searching for my grandmother's family

My grandmother Mary Isabell Gillespie was born in Ireland and came to the United States when she was only 3. Traveling with her in 1898 were her mother Jennie O’Rourke Gillespie, her brother Lawrence Gillespie (age 10) and her twin sister Rose Ann Gillespie (age 3). There is a family tradition that says her grandmother Bridget O’Rourke traveled with them, but I have not found any record of her.

Before my grandmother came to the States, her uncles traveled to Ohio first. In 1886 her uncle James (a.k.a. John) O’Rourke traveled to the United States. I believe this to be a scouting trip to decide where to settle. James must have returned to Ireland and in 1893 James returned to the U.S. with his brother Thomas O’Rourke. They arrived at the port of Philadelphia and settled in Columbiana County, Ohio and started work in the coal mines.

After Jennie’s husband (his name may be Owen) died, she sailed to the U.S. in 1898 with her 3 children and according to a family story her mother Bridget O’Rourke. They settled in with Jennie’s brothers and purchased a farm in about 1900. They did well and my grandmother and her sister lived on the farm until each of them married. Their mother passed away in 1921 and their Uncle Thomas sold the farm in 1928.

The family tradition also says that the family was from County Meath.  There wasn’t any mention of a parish. The only other hint I have is that stone fences were common in the area where the family lived in Ireland. The farm was covered in stones and my great-grandmother and her brothers built stone fences on the farm in Ohio. They became a subject of curiosity in the 1960’s which is how I received so much information.

Is there some way for me to determine their parish? What is the best website to search for records?