As filed with the U.S. Securities and Exchange Commission on August 22, 2019

File Nos. 333-179904 and 811-22649

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	☒
Post-Effective Amendment No. 508	☒
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	☒
Amendment No. 508	☒

(Check appropriate box or boxes)

iShares U.S. ETF Trust

(Exact Name of Registrant as Specified in Charter)

c/o State Street Bank and Trust Company

1 Lincoln Street

Mail Stop SUM0703

Boston, MA 02111

(Address of Principal Executive Office)(Zip Code)

Registrant’s Telephone Number, including Area Code: (415) 670-2000

The Corporation Trust Company

1209 Orange Street

Wilmington, DE 19801

(Name and Address of Agent for Service)

With Copies to:

MARGERY K. NEALE, ESQ.	DEEPA DAMRE, ESQ.
WILLKIE FARR & GALLAGHER LLP	BLACKROCK FUND ADVISORS
787 SEVENTH AVENUE	400 HOWARD STREET
NEW YORK, NY 10019-6099	SAN FRANCISCO, CA 94105

It is proposed that this filing will become effective (check appropriate box):

☐ Immediately upon filing pursuant to paragraph (b)

☒ On September 20, 2019, pursuant to paragraph (b)

☐ 60 days after filing pursuant to paragraph (a)(1)

☐ On (date) pursuant to paragraph (a)(1)

☐ 75 days after filing pursuant to paragraph (a)(2)

☐ On (date) pursuant to paragraph (a)(2)

If appropriate, check the following box:

☒ The post-effective amendment designates a new effective date for a previously filed post-effective amendment.

Explanatory Note

This Post-Effective Amendment No. 508 to the Registrant’s Registration Statement on Form N-1A is being filed pursuant to paragraph (b)(1)(iii) of Rule 485 of the Securities Act of 1933, as amended (the “1933 Act”), solely for the purpose of delaying, until September 20, 2019, the effectiveness of the registration statement for the iShares California Short Maturity Muni Bond ETF (the “Fund”), filed in Post-Effective Amendment No. 480 on April 11, 2019, pursuant to paragraph (a) of Rule 485 of the 1933 Act.

The effectiveness of the Registration Statement of the Fund was previously delayed pursuant to paragraph (b)(1)(iii) of Rule 485 of the 1933 Act as follows:

PEA No.	Date Filed	Automatic Effective Date
493	June 24, 2019	June 28, 2019
494	June 27, 2019	July 26, 2019
501	July 25, 2019	August 23, 2019

This Post-Effective Amendment No. 508 incorporates by reference the information contained in Parts A, B and C of Post-Effective Amendment No. 480.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all the requirements for the effectiveness of this Registration Statement pursuant to Rule 485(b)(1)(iii) of the Securities Act of 1933, as amended, and has duly caused this Post-Effective Amendment No. 508 to the Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of San Francisco and the State of California on the 22^nd day of August, 2019.

iSHARES U.S. ETF TRUST 

By:
	Martin Small*
	President
	Date: August 22, 2019

Pursuant to the requirements of the Securities Act of 1933, as amended, this Post-Effective Amendment No. 508 to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

By:
	Salim Ramji**
	Trustee
	Date: August 22, 2019
	John E. Martinez*
	Trustee
	Date: August 22, 2019
	Cecilia H. Herbert*
	Trustee
	Date: August 22, 2019
	John E. Kerrigan*
	Trustee
	Date: August 22, 2019
	Robert S. Kapito*
	Trustee
	Date: August 22, 2019

	Madhav V. Rajan*
	Trustee
	Date: August 22, 2019
	Jane D. Carlin*
	Trustee
	Date: August 22, 2019
	Drew E. Lawton*
	Trustee
	Date: August 22, 2019
	Richard L. Fagnani*
	Trustee
	Date: August 22, 2019
	/s/ Neal J. Andrews
	Neal J. Andrews*
	Treasurer and Chief Financial Officer
	Date: August 22, 2019
*By:	/s/ Neal J. Andrews
	Neal J. Andrews
	Attorney-in-fact
	Date: August 22, 2019

* Powers of Attorney, each dated April 1, 2019, for Martin Small, Jane D. Carlin, Cecilia H. Herbert, John E. Kerrigan, John E. Martinez, Madhav V. Rajan, Robert S. Kapito, Drew E. Lawton, Richard L. Fagnani and Neal J. Andrews are incorporated herein by reference to Post-Effective Amendment No. 474, filed April 4, 2019.

** Power of Attorney, dated June 19, 2019, for Salim Ramji is filed herein by reference to Post-Effective Amendment No. 493, filed June 24, 2019.