It’s one of the most frustrating things to have to deal with – your ancestor goes a-wandering but you have no idea to where. It can be tricky but there are a few things worth considering.
Firstly, identify the most likely places your ancestors would move to. The foremost reason they would move is for work, so look at areas where there might have been similar employment – textiles workers might move from the Cotswolds to Yorkshire or Lancashire, coal miners from South Wales to the North-East, and of course just about everyone was pouring from the countryside into the cities. Look for common migration patterns from your area of interest – where were other people from that area going? Some basic historical research might give you some interesting possibilities.
It’s also worth considering other possibilities though. They might have moved to the area that their spouse came from. Bear in mind also that sometimes women would go back to their family in order to have the baby, so keep an eye out for people living in one region but born in another, to find out where their family might originate from. On the other hand, families often tended to move together, so if you find a sibling who has moved away, look nearby for people who seem to be missing from their original location. Also, sometimes you get grandchildren living with grandparents or other family members, which might give some indication of where someone has moved to or from.
Bear in mind that the further away an ancestor moves from the place they were born, the vaguer the census entry for place of birth may be. Census enumerators were unlikely to have been familiar with far-off localities, so often just wrote down larger places they had heard of or even just the county. Sometimes it all gets a bit muddled for no apparent reason. Don’t discount a possible ancestor just because his or her place of birth is a little off!
On the other hand, look out for recurring locations and addresses – if there seems to be a pattern, it’s highly unlikely that it’s random. Families would often move very short distances within their locale, so if there’s someone with the same family name on the same street, there’s a strong chance their connected somehow, even if you can’t figure it out yet. Similarly, I often find children who marry end up living very lose to their parents, so if you can’t track a marriage down, try looking at the neighbours of known family for possibilities.