With the second highest inmate population in the country Texas's county jails stay pretty busy. Texas is famous for taking a hard line with crime so it's no surprise that they have one of the highest per capita inmate populations in the country.

Why are there so many inmates in Texas county jails?
First of all, there are a lot of counties in Texas. There are 254 to be exact, more counties than any other state in the US. While some of these counties are extremely small (Loving County, for example, has only 74 people living within the county lines), Texas also has some giant counties. Harris County (home of Houston) has over 3.5M residents.

Dallas, Tarrant and Bexar each have over 1M residents as well. When you have a lot of people you inevitably have a lot more people to lock up as well.

County jails vs. prisons
If you committed a very serious crime (think murder, grand theft auto, armed robbery, etc.), you probably won't spend much time in a county jail. You will go to a county jail until you are sentenced and you will spend the rest of your time (and possibly the rest of your life) in prison.

Prisons are a lot rougher than jails because the inmates have been charged with more serious crimes and spend a lot more time behind bars. It is very rare to spend more than a year in a county jail (during any single stay). Generally inmates don't want to risk catching another charge in county jail so they don't fight as often and try to be model inmates.