In the interest of teaching you to fish, FamilySearch has the best collection of "free" indexed record IMO. These include censuses, marriages, births, deaths, draft cards, some immigration records. Their collection is ever growing as they have a large set of volunteer indexers. I've done some indexing for them, their setup makes it easy, I figure it's my due for all the searching I do.
You can get to the FamilySearch search page and others from profiles here, but I keep forgetting where, and I have the URL, so I just go directly: https://familysearch.org/search
Fill in the fields that seem important to you, press the search button, and records will come out. Compare the information carefully to what you know about the family you are researching. You might get different results if you mix things up a bit. For the question you posted, I might try:
William Christopher McClure, birth 1853 Maryland
William Christopher McClure, father John J McClure
John J McClure, birth 1813 to 1833
George McClure, birth year, (I'm guessing you have at least a good estimate, but you didn't share), state if you have it
George McClure, father William Christopher McClure
The best matched records will be at the top, though I've found some good ones past the "not quite, but may still be of interest" line. If you get too many records, add more search terms that will narrow it down. Cap things by guessing at birth and/or death dates.
I like birth, marriage and death records for tying parents and children together, censuses are great for tying whole families together. There is useful information on WWI and WWII draft cards, but I would skip enlistment records for the Civil War or earlier unless you are looking for a very unique name. As I've been untangling confused McClure records recently, I can tell you that you will find tons of Georges, Williams, and Johns. Pay attention to birth dates, places of residence, parent/child information you find. If you get back to the 1700s, you'll find they kept using the same handful of names over and over again, so there are many Halberts/Alexanders/Georges/Thomases/Johns, all living in the same area, related (nephews, cousins, sons) but not the same. If you happen to end up in my branches, I have some sources (genealogy books on paper) that may help.