Last year (and I think it's the same this year) there are 32 roster spots for each team. 20 position players, 12 pitchers, at least 3 of those are relievers (in practice, you'll note many more relievers than that are usually chosen, but not by me).
I do this All-Star selection every year - I do not recall a year where it was more challenging to get a representative from every team as it is with the AL this year.
AL East
1. Bos 101
2. NYY 101
3. Tampa
4. Tor
5. Balt
AL Central
1. Cleve 94
2. Min
3. Det
4. CWS
5. KC
AL West
1. Hou 103
2. Sea 89
3. LAA 84
4. Oak
5. Tex
NL East
1. Wash 90
2. Atl 89
3. Phil 86
4. NYM
5. Mia
NL Cen
1. Chi 92
2. Mil 89
3. StL 85
4. Pit
5. Cin
NL West
1. LAD 89
2. Ariz 87
3. SFG 80
4. Col
5. SD
NL
C JT Realmuto Mia 3.05
W.Contreras Chi 2.45
F.Cervelli Pit 2.2
1B F.Freeman Atl 4.2-MVP
J.Votto Cin 3.45
P.Goldschmidt Ari 3
B.Belt SFG 2.3
2B S.Gennett Cin 2.75
O.Albies Atl 2.65
J.Baez Chi 2.55
SS T.Turner Wash 3.05
B.Crawford SFG 2.6
3B N.Arenado Col 3.4
E.Suarez Cin 2.9
T.Shaw Mil 2.4
LF B.Nimmo NYM 2.95
CF L.Cain Mil 3.6
O.Herrera Phi 2.75
M.Taylor Wash 2.2
RF N.Markakis Atl 3.2
SP
J. DeGrom NYM 4.55-Cy
M.Scherzer Wash 4.15
A.Nola Phi 4.05
R.Stripling LAD 2.9
K.Freeland Col 2.9
J.Lester Chi 2.7
M.Mikolas StL 2.6
M. Foltynewicz Atl 2.4
P.Corbin Ari 2.35
RP S.Doolittle Wash 2.1
A.Ottavino Col 2
K.Yates SD 1.65
AL
C M.Stassi Hou 1.5
W.Ramos TB 1.4
W.Ramos TB 1.4
1B M.Olson Oak 2.1
M.Moreland Bos 1.9
2B J.Altuve Hou 3.6
J.Lowrie Oak 2.25
SS F.Lindor Cle 4.45
C.Correa Hou 3.05
C.Correa Hou 3.05
A.Simmons LAA 2.8
J.Segura Sea 2.6
3B J.Ramirez Cle 4.55
M.Chapman Oak 3.25
LF E.Rosario Min 3.05
CF M.Trout LAA 5.85-MVP
RF M.Betts Bos 4.25
A.Judge NYY 3.75
M.Haniger Sea 3.05
M.Haniger Sea 3.05
G.Springer Hou 2.75
DH JD Martinez Bos 3.45
M.Davidson CWS 1.1
M.Davidson CWS 1.1
SP C.Kluber Cle 4.4-Cy
J.Verlander Hou 4.05
L.Severino NYY 3.95
C.Sale Bos 3.75
T.Bauer Cle 2.9
B.Snell TB 2.85
L.Severino NYY 3.95
C.Sale Bos 3.75
T.Bauer Cle 2.9
B.Snell TB 2.85
C.Hamels Tex 2
JA Happ Tor 2
JA Happ Tor 2
M.Boyd Det 1.35
RP A.Chapman NYY 2.5
K.Herrera KC 1.9
R.Bleier Balt 1.6
K.Herrera KC 1.9
R.Bleier Balt 1.6