I found this in the Nashville forum on UP. It's a list of the U.S. Metros that had 100,000+ population in 1950.
Most Metros back then were probably one county. Notice how the industrial NE and Rust Belt cities dominate the list and how insignificant Austin was back then. Corpus was bigger than Austin and catching El Paso was only a dream.
Metropolitan Areas -- 1950
1.New York -- 12,911,994
2.Chicago -- 5,495,364
3.Los Angeles -- 4,367,911
4.Philadelphia -- 3,671,048
5.Detroit -- 3,016,197
6.Boston -- 2,875,876
7.San Francisco -- 2,240,767
8.Pittsburgh -- 2,213,236
9.St. Louis -- 1,681,281
10.Cleveland -- 1,465,511
11.Washington -- 1,464,089
12.Baltimore -- 1,337,373
13.Minneapolis -- 1,116,509
14.Buffalo -- 1,089,230
15.Cincinnati -- 904,402
16.Milwaukee -- 871,047
17.Kansas City -- 814,357
18.Houston -- 806,701
19.Seattle -- 732,992
20.Portland -- 704,829
21.New Orleans -- 685,405
22.Providence -- 681,815
23.Atlanta -- 671,797
24.Dallas -- 614,799
25.Louisville -- 576,900
26.Denver -- 563,832
27.Birmingham -- 558,928
28.San Diego -- 556,808
29.Indianapolis -- 551,777
30.Worcester -- 546,401
31.New Haven -- 545,784
32.Hartford -- 539,661
33.Youngstown -- 528,498
34.Albany -- 514,490
35.Bridgeport -- 504,342
36.Columbus -- 503,410
37.San Antonio -- 500,460
38.Miami -- 495,084
39.Rochester -- 487,632
40.Memphis -- 482,393
41.Dayton -- 457,333
42.Springfield -- 455,565
43.Norfolk -- 446,200
44.Allentown -- 437,824
45.Akron -- 410,032
46.Tampa -- 409,143
47.Toledo -- 395,551
48.Wilkes-Barre -- 392,241
49.New Bedford -- 381,569
50.Omaha -- 366,395
51.Fort Worth -- 361,253
52.Wheeling -- 354,092
53.Honolulu -- 353,020
54.Syracuse -- 341,719
55.Knoxville -- 337,105
56.Phoenix -- 331,770
57.Richmond -- 328,050
58.Oklahoma City -- 325,352
59.Charleston -- 322,072
60.Nashville -- 321,758
61.Jacksonville -- 304,029
62.Harrisburg -- 292,241
63.Johnstown -- 291,354
64.San Jose -- 290,547
65.Grand Rapids -- 288,292
66.Utica -- 284,262
67.Canton -- 283,194
68.San Bernardino -- 281,642
69.Sacramento -- 277,140
70.Fresno -- 276,515
71.Tacoma -- 275,876
72.Salt Lake City -- 274,895
73.Flint -- 270,963
74.Wilmington -- 268,387
75.Scranton -- 257,396
76.Reading -- 255,740
77.Duluth -- 252,777
78.Tulsa -- 251,686
79.Peoria -- 250,512
80.Chattanooga -- 246,453
81.Huntington -- 245,795
82.Lancaster -- 234,717
83.Davenport -- 234,256
84.Mobile -- 231,105
85.Trenton -- 229,781
86.Des Moines -- 226,010
87.Wichita -- 222,290
88.Spokane -- 221,561
89.Erie -- 219,388
90.South Bend -- 205,058
91.York -- 202,737
92.Stockton -- 200,750
93.Charlotte -- 197,052
94.Little Rock -- 196,685
95.Beaumont -- 195,083
96.El Paso -- 194,968
97.Greensboro -- 191,057
98.Brockton -- 189,468
99.Binghamton -- 184,698
100.Fort Wayne -- 183,722
101.Shreveport -- 176,547
102.Lansing -- 172,941
103.Columbus -- 170,541
104.Madison -- 169,357
105.Portland -- 169,201
106.Greenville -- 168,152
107.Corpus Christi -- 165,471
108.Charleston -- 164,856
109.Augusta -- 162,013
110.Austin -- 160,980
111.Evansville -- 160,422
112.Baton Rouge -- 158,236
113.Manchester -- 156,987
114.Saginaw -- 153,515
115.Rockford -- 152,385
116.Savannah -- 151,481
117.Lorain -- 148,162
118.Hamilton -- 147,203
119.Albuquerque -- 145,673
120.Winston-Salem -- 146,135
121.Columbia -- 142,565
122.Jackson -- 142,164
123.Altoona -- 139,514
124.Montgomery -- 138,965
125.Raleigh -- 136,450
126.Macon -- 135,043
127.Roanoke -- 133,407
128.Pittsfield -- 132,966
129.Atlantic City -- 132,399
130.Springfield -- 131,484
131.Waco -- 130,194
132.Kalamazoo -- 126,707
133.Asheville -- 124,403
134.Lincoln -- 119,742
135.Orlando -- 114,950
136.Galveston -- 113,066
137.Springfield -- 111,661
138.Racine -- 109,585
139.Jackson -- 107,925
140.Topeka -- 105,418
141.Terre Haute -- 105,160
142.Springfield -- 104,823
143.Cedar Rapids -- 104,274
144.Sioux City -- 103,917
145.Durham -- 101,639
146.Lubbock -- 101,048
147.Lexington -- 100,746
148.Waterloo -- 100,448
http://www.demographia.com/dm-usmet-fr50.htm