City and county jails in the US held 734,500 people at on June 28, 2019. ("Rates are based on the number of inmates held on the last weekday in June.") Note: the jail population figure is only a one-day snapshot. There were a total of 10,300,000 admissions to jails in the US throughout calendar year 2019.

Demographics of the jail population on that date are as follows:
623,700 male, 110,700 female.
Juveniles: 2,200 held as adults, 700 held as juveniles.
Racial demographics were as follows:
White: 362,900
Black: 247,100
Latinx: 106,900
American Indian/Alaska native: 10,200
Asian/native Hawaiian/other Pacific islander: 4,700
"Other," including two or more races: 2,600

Only 253,700 people confined to a local jail had been convicted of any crimes and had either already been sentenced or were awaiting sentencing. The remaining 480,700 people confined to local jails were unconvicted and awaiting court action on a current charge.

"An estimated 224 inmates per 100,000 U.S. residents were incarcerated in local jails nationwide at midyear 2019. Blacks were jailed at a rate of 600 per 100,000 black U.S. residents (table 2). American Indians and Alaska Natives (AIANs) had a jail incarceration rate of 420 per 100,000 AIAN U.S. residents. Whites (184 per 100,000 white U.S. residents) and Hispanics (176 per 100,000 Hispanic U.S. residents) were jailed at similar rates. Asians were incarcerated in jails at a rate of 25 inmates per 100,000 Asian U.S. residents.

"From 2008 to 2019, the overall jail incarceration rate decreased 13%. The rate grew 10% for whites (from 167 to 184 per 100,000). It fell 27% for blacks (from 825 to 600 per 100,000), 32% for Asians (from 37 to 25 per 100,000), and 36% for Hispanics (from 273 to 176 per 100,000). The rate change for AIANs (from 386 to 420 per 100,000) was not statistically significant during this period.

"The male incarceration rate fell 16% from 2008 to 2019, declining from 457 to 386 inmates per 100,000 male U.S. residents. Females were incarcerated at a rate of 66 inmates per 100,000 female U.S. residents at midyear 2019, similar to their rate of 65 per 100,000 in 2008. The black jail population declined 20% from 2008 to 2019

"From 2008 to 2019, the total jail population declined 6% (down 51,000 inmates) (table 3). During this period, the number of black inmates (down 20%), Hispanic inmates (down 17%), and Asian inmates (down 6%) decreased, even though the overall number of blacks (up 10%), Hispanics (up 29%), and Asians (up 42%) in the U.S. increased (not shown in tables). The number of white inmates increased 9% from 2008 to 2019, while the change in the number of AIAN inmates was not statistically significant."

Source

Zhen Zeng, PhD, and Todd D. Minton. Jail Inmates In 2019. Washington, DC: US Department of Justice Bureau of Justice Statistics. March 2021. NCJ255608.