United Airlines operates two versions of the Airbus A319. The second type (the 19G) joined the United fleet from China Southern Airlines and while the cabin was reconfigured to match UA's standard 12F 136M layout, the galley and toilets at the rear of the aircraft are different from the rest of the fleet. Both diagrams are included below.
Both types include 36 designated Economy Plus seats (indicated with blue grey accents).

Diagram updated 31 Oct 2021
Domestic First
Twelve Safran articulated cradle seats arranged in a 2-2 configuration, featuring a six-way adjustable headrest, flip-up tablet holder, in-arm storage pocket
Row pitch: 37.0"
Seat width: 20"
Seat recline: 5"
Notes:
There are no footwell cut outs at the base of the forward bulkheads
Economy Plus (seats indicated with blue grey accents)
Thirty-six Recaro BL3530 slimline seats featuring a 4 way adjustable headrest and a tablet holder are arranged in a 3-3 configuration
Row pitch: 33.5" standard; 38.0" at row 21
Seat width: 17.5"
Seat recline: 3"
Notes:
Row 7 seats have usable space beneath the row 3 seats and have fixed armrests containing retractable bi-fold tray tables; seat width: 17.0"
Seats in row 15 do not recline
Economy
78 Recaro BL3530 slimline seats featuring a 4 way adjustable headrest and a tablet holder are arranged in a 3-3 configuration
Row pitch: 30.1"
Seat width: 17.5"
Seat recline: 2"
Wifi:
ViaSat KA-band
Power:
First and Economy Plus seats are equipped with universal AC (110V) sockets
In-flight entertainment:
Content streamed to your personal electronic device. The seats on this aircraft type do not have screens

Diagram updated 13 Apr 2022