When you find that a baptism, marriage or burial happened before the earliest record in the church where you have been finding the family records, you want to know which church in the area has earlier records. People moved back and forth from Colotlan to Tlaltenango and other nearby places, making the research more of a challenge since these are in two different states -- which have very erratic borders. So I created a map of the area, showing the earliest baptism year for each parish, taken from the FamilySearch record collection titles for that church.
I have posted the map at http://www.wwjohnston.net/famhist/#mexican
If you see any churches that I have missed for people in the Colotlan-Tlaltenango area, please let me know. I have intentionally not included churches that began in the 1900's. So the intent is to be able to assume that any place shown without a date either had no church prior to 1900.
    Wesley Johnston