Simon Chen, Wikipedia is generally a poor source on criminal groups and anybody can add their information to it. Texas Syndicate is a large ( everything is bigger in Texas smile ) prison gang throughout but the updated estimates are 4,400 members in total for prisons & streets.
The Source : https://www.dps.texas.gov/director_staff/media_and_communications/2014/txGangThreatAssessment.pdf

Generally speaking prison gangs are more exclusive/selective on their membership but some street gangs are too.

If you think you are too small to make a difference, you haven't spend the night with a mosquito.
- African Proverb