In 1937, the Rock Island took the plunge into streamlining in a big way. It ordered six new lightweight stainless-steel trainsets from Budd, which were to become the Rockets. Their design shows some evolution from the original pioneering articulated streamliners: While the coach and dinette-coach sections were articulated, the trailing parlor-lounge observation car was of completely separate construction and a conventional diesel locomotive (a 1200 horsepower "TA" from Electro-Motive) provided the motive power. This semi-articulated design was to prove fortuitous when wartime exigencies necessitated a reshuffling of equipment; by replacing the dinette section with crew dormitory space and inserting a full dining car and a streamlined sleeper between the articulated coaches and the parlor-observation, the Rock Island  expeditiously converted three of the original daytime-only trains into streamlined long-distance equipment to handle the load of the new Twin Star Rocket.

The trains shown in this timetable were four-car sets, with a triple-unit articulated coach which featured a baggage compartment and 32 dinette seats with a small pantry and kitchen in the forward unit. Bringing up the markers was the parlor-lounge-observation car. The Peoria Rocket entered service on September 19, 1937 making two round trips a day between Chicago and Peoria, while the Des Moines Rocket began making its single round trip a day a week later on September 26[*].


From the pages of the Official Guide, September 1938

Chicago, Rock Island & Pacific herald

The Peoria Rocket
The Des Moines Rocket

Chicago, Rock Island & Pacific
July 30, 1938

505 501 503 Train Number 506 502 504
Daily Daily Daily Miles Services Daily Daily Daily
5 45P 11 00A 7 00P Dp 0.0 Chicago, IL (La Salle St. Sta.) (CT) T C Ar 1 15P 9 40A 5 40P
5 54P 11 09A 7 09P 6.6 Englewood, IL (63rd St.) T C 1 04P 9 28A 5 28P
RF RF RF 40.4 Joliet, IL T C DF DF DF
RF 12 18P 8 18P 84.5 Ottawa, IL T C DF 8 14A 4 14P
RF 12 33P 8 33P 99.1 La Salle, IL T C DF 7 59A 3 59P
RF 7 32P N N Ar 114.2 Bureau, IL T C Dp 11 20A N N
The Peoria Rocket 222
N N Dp 114.2 Bureau, IL T C Ar 11 10A N N
1 40P 9 40P Ar 161.4 Peoria, IL (Rock Island Depot) (CT) T C Dp 10 00A 7 00A 3 00P
210 Connecting Train Number 227
5 30P Dp 0.0 Peoria, IL (Rock Island Depot) (CT) T C Ar 1 25P
6 30P Ar 46.8 Bureau, IL T C Dp 12 20P
The Des Moines Rocket
RF 7 32P Dp 114.2 Bureau, IL T C Ar 11 20A
8 30P 179.3 Moline, IL T C 10 24A
8 38P 181.2 Rock Island, IL T C 10 19A
8 44P 182.8 Davenport, IA T C 10 11A
9 43P 236.9 Iowa City, IA (Wright St.) T C 9 14A
DF 302.6 Grinnell, IA T C RF
DF 322.7 Newton, IA T C RF
11 45P Ar 357.7 Des Moines, IA (CT) T C Dp 7 15A

Train 501 (Chicago-Peoria): 3 stops, 2:40, 60.5 MPHTrain 502 (Peoria-Chicago): 3 stops, 2:40, 60.5 MPH

Train 503 (Chicago-Peoria): 3 stops, 2:40, 60.5 MPHTrain 504 (Peoria-Chicago): 3 stops, 2:40, 60.5 MPH

Train 505 (Chicago-Des Moines): 6 stops, 6:00, 59.6 MPHTrain 506 (Des Moines-Chicago): 6 stops, 6:00, 59.6 MPH

Rock Island Lines
Route of the Golden State Limited

THROUGH CAR EQUIPMENT—
Westbound

ROCKET TRAINS

The ROCKETS are not excess fare trains. However, all seats, both coach and parlor lounge, are reserved, individually assigned in advance.

No. 501—♦CHICAGO-PEORIA—Daily.
Parlor Lounge Car, Dinette Coach, Coaches—
Chicago to Peoria.

No. 503—♦CHICAGO-PEORIA—Daily.
Parlor Lounge Car, Dinette Coach, Coaches—
Chicago to Peoria.

No. 505—♦CHICAGO-DES MOINES. Daily.
Parlor Lounge Car, Dinette Coach, Coaches—
Chicago to Des Moines.

♦ Air-Conditioned.

Rock Island Lines
Route of the Rocky Mountain Limited


THROUGH CAR EQUIPMENT—Eastbound

ROCKET TRAINS

The ROCKETS are not excess fare trains. However, all seats, both coach and parlor lounge, are reserved, individually assigned in advance.

No. 502—♦PEORIA-CHICAGO—Daily.
Parlor Lounge Car, Dinette Coach, Coaches—
Peoria to Chicago.

No. 504—♦PEORIA-CHICAGO—Daily.
Parlor Lounge Car, Dinette Coach, Coaches—
Peoria to Chicago.

No. 506—♦DES MOINES-CHICAGO—Daily.
Parlor Lounge Car, Dinette Coach, Coaches—
Des Moines to Chicago.

♦ Air-Conditioned.

A June 1938 analysis showed that the Rockets were enormously popular...and profitable. For the first (partial) year of operation, the Rock Island reported that the Peoria Rocket cleared $314,688 of revenue against direct expenses of $93,814, while the Des Moines Rocket had $353,956 revenue and $99,128 of direct expenses...an operating profit margin of over 70 percent![*] (Note, however, that this does not include capital expenditures or right-of-way and signal maintenance and expenses, which would change those figures significantly.) Even the food service made money...a rarity in any railroad's passenger operations.