E175 bases:
DEN - United
ORD - United
SEA - Alaska and Delta
PDX - Pretty much just Alaska
SFO - United and Delta
LAX - United and Delta

CRJ:
DTW - DL
MSP - DL
ORD - DL, UA, AA
IAH - DL and UA
DEN - Mostly UA, some DL, some AA for Aspen and Eagle
COS - UA, DL
SLC - DL, some UA
PHX - AA
TUS - UA, some DL, lots of maintenance type flights
FAT - UA, some DL
LAX - UA, DL, AA
SFO - United mostly
SEA - Mostly DL
PSP - United, some AA and maybe some DL

Things always change and move around. A delta pairing or two have popped up on the E175 for example in PDX and DEN. FAT guys just started doing more DL flying. IAH guys started doing more DL lately. Things are always changing and getting shifted around.