USPS EXAM 421 (WINDOW CLERK)
2026/2027 LATEST EDITION | REAL
EXAM-BASED QUESTIONS & VERIFIED
ANSWERS TO PASS ON YOUR FIRST
TRY
This 2025/2026 updated resource provides verified questions and 100%
accurate answers for the USPS Exam 421, designed for candidates applying
to the Window Clerk position. The content reflects the latest exam format
and includes sections on address checking, forms completion, postage
calculations, customer service scenarios, and error identification. Ideal for
applicants preparing to pass the U.S. Postal Service clerk assessment with
confidence.
1. What is the primary mission of the USPS?
A. Make a profit
B. Deliver mail faster than private carriers
C. Provide reliable, affordable, universal service
D. Compete with UPS and FedEx
⬛ Answer: C
Rationale:
USPS is not a for-profit company. Its mission is universal service,
meaning everyone in the U.S. receives mail at affordable rates,
regardless of location.
,2. What does “sanctity of the mail” mean?
A. Mail is delivered faster
B. Mail must be profitable
C. Mail is protected from theft and tampering
D. Mail is sorted by priority
⬛ Answer:
C Rationale:
Sanctity of the mail refers to protecting mail from being opened, stolen,
delayed, or damaged. Customer trust depends on mail security.
3. Which clock system does USPS use?
A. 12-hour
B. Military clock
C. 24-hour clock
D. Local time only
⬛ Answer:
C Rationale:
USPS uses a 24-hour clock to avoid confusion in operations,
transportation, and scheduling.
4. What is an APC?
A. Automated Package Center
B. Automated Postal Center
,C. Advanced Postal Counter
D. Authorized Postal Contractor
⬛
Answer: B
Rationale:
APCs are self-service kiosks where customers can buy postage and mail
items without clerk assistance.
5. What is Critical Entry Time (CET)?
A. Time mail arrives at the post office
B. Deadline for mail to be processed for dispatch
C. Time carriers leave for routes
D. Time customers arrive
⬛ Answer: B
Rationale:
CET determines when mail must be accepted to meet transportation and
delivery schedules.
6. Clearance Time refers to:
A. Opening time of the post office
B. Time mail is cleared for dispatch
C. End of customer service
D. Final delivery time
⬛ Answer: B
, Rationale:
Clearance time is when mail leaves the facility for transportation.
7. Maximum weight for First-Class Mail letters?
A. 10 oz
B. 13 oz
C. 15 oz
D. 20 oz
⬛ Answer: B
Rationale:
First-Class Mail letters and packages have a maximum weight of 13
ounces.
8. Which service provides proof of mailing but NOT
delivery confirmation?
A. Certified Mail
B. Registered Mail
C. Certificate of Mailing
D. Priority Mail
⬛ Answer:
C Rationale:
Certificate of Mailing only proves an item was mailed, not delivered.
G. Which form is used for Certified Mail?
2026/2027 LATEST EDITION | REAL
EXAM-BASED QUESTIONS & VERIFIED
ANSWERS TO PASS ON YOUR FIRST
TRY
This 2025/2026 updated resource provides verified questions and 100%
accurate answers for the USPS Exam 421, designed for candidates applying
to the Window Clerk position. The content reflects the latest exam format
and includes sections on address checking, forms completion, postage
calculations, customer service scenarios, and error identification. Ideal for
applicants preparing to pass the U.S. Postal Service clerk assessment with
confidence.
1. What is the primary mission of the USPS?
A. Make a profit
B. Deliver mail faster than private carriers
C. Provide reliable, affordable, universal service
D. Compete with UPS and FedEx
⬛ Answer: C
Rationale:
USPS is not a for-profit company. Its mission is universal service,
meaning everyone in the U.S. receives mail at affordable rates,
regardless of location.
,2. What does “sanctity of the mail” mean?
A. Mail is delivered faster
B. Mail must be profitable
C. Mail is protected from theft and tampering
D. Mail is sorted by priority
⬛ Answer:
C Rationale:
Sanctity of the mail refers to protecting mail from being opened, stolen,
delayed, or damaged. Customer trust depends on mail security.
3. Which clock system does USPS use?
A. 12-hour
B. Military clock
C. 24-hour clock
D. Local time only
⬛ Answer:
C Rationale:
USPS uses a 24-hour clock to avoid confusion in operations,
transportation, and scheduling.
4. What is an APC?
A. Automated Package Center
B. Automated Postal Center
,C. Advanced Postal Counter
D. Authorized Postal Contractor
⬛
Answer: B
Rationale:
APCs are self-service kiosks where customers can buy postage and mail
items without clerk assistance.
5. What is Critical Entry Time (CET)?
A. Time mail arrives at the post office
B. Deadline for mail to be processed for dispatch
C. Time carriers leave for routes
D. Time customers arrive
⬛ Answer: B
Rationale:
CET determines when mail must be accepted to meet transportation and
delivery schedules.
6. Clearance Time refers to:
A. Opening time of the post office
B. Time mail is cleared for dispatch
C. End of customer service
D. Final delivery time
⬛ Answer: B
, Rationale:
Clearance time is when mail leaves the facility for transportation.
7. Maximum weight for First-Class Mail letters?
A. 10 oz
B. 13 oz
C. 15 oz
D. 20 oz
⬛ Answer: B
Rationale:
First-Class Mail letters and packages have a maximum weight of 13
ounces.
8. Which service provides proof of mailing but NOT
delivery confirmation?
A. Certified Mail
B. Registered Mail
C. Certificate of Mailing
D. Priority Mail
⬛ Answer:
C Rationale:
Certificate of Mailing only proves an item was mailed, not delivered.
G. Which form is used for Certified Mail?
