Loss before income taxes for the U.S. for years ended December 31, 2020, 2019 and 2018 are $917 million, $500 million, and $343 million, respectively. Loss before income taxes for non-U.S. jurisdictions for years ended December 31, 2020, 2019 and 2018 are $14.2 million, $30.5 million, and $24.3 million, respectively.

Components of the income tax provision applicable to federal, state and foreign income taxes for the years ended December 31, 2020, 2019 and 2018 are as follows (in thousands):

	2020			2019			2018
Federal income tax benefit:
Current	$	(1,977	)	$	(1,976	)	$	(3,954	)
Deferred		(107,334	)		(90,441	)		(35,081	)
		(109,311	)		(92,417	)		(39,035	)
State income tax expense (benefit):
Current		225			851			1,704
Deferred		(17,949	)		(11,593	)		(11,147	)
		(17,724	)		(10,742	)		(9,443	)
Foreign income tax expense (benefit):
Current		(291	)		(348	)		(2,552	)
Deferred	—				(1,168	)		5,043
		(291	)		(1,516	)		2,491
Total income tax benefit:
Current		(2,043	)		(1,473	)		(4,802	)
Deferred		(125,283	)		(103,202	)		(41,185	)
Total income tax benefit:	$	(127,326	)	$	(104,675	)	$	(45,987	)

The difference between the statutory federal income tax rate and the effective income tax rate for the years ended December 31, 2020, 2019 and 2018 is summarized as follows:

	2020			2019			2018
Statutory tax rate		21.0	%		21.0	%		21.0	%
State income taxes - net of the federal income tax benefit		1.7			1.4			1.1
Goodwill impairment		(8.2	)		(0.7	)		(6.9	)
Permanent differences		(0.6	)		(1.2	)		(0.7	)
Tax effects of tax reform		—			—			(1.3	)
Valuation allowance		(0.2	)		(0.8	)		(3.7	)
State deferred tax remeasurement		—			(1.1	)		2.3
Other differences, net		—			1.1			0.7
Effective tax rate		13.7	%		19.7	%		12.5	%

The effective tax rate decreased by approximately 6.0% to 13.7% for 2020 compared to 19.7% for 2019. This difference was primarily due to higher goodwill impairment charges in 2020 relative to 2019, which are not deductible for tax purposes. These charges resulted in a 8.2% decrease to the effective tax rate in 2020, as compared to a 0.7% decrease to the effective tax rate in 2019.

The tax effect of temporary differences and tax attributes representing deferred tax assets and liabilities at December 31, 2020 and 2019 are as follows (in thousands):

	2020			2019
Deferred tax assets:
Net operating loss carryforwards	$	370,875		$	375,308
Tax credits		4,918			4,138
Expense associated with stock-based compensation		11,252			10,561
Workers' compensation allowance		17,177			19,536
Other deferred tax asset		24,735			21,698
		428,957			431,241
Less:
Valuation allowance		(19,133	)		(17,231	)
Total deferred tax assets		409,824			414,010
Deferred tax liabilities:
Property and equipment basis difference		(475,025	)		(607,785	)
Other		(12,475	)		(9,184	)
Total deferred tax liabilities		(487,500	)		(616,969	)
Net deferred tax liability	$	(77,676	)	$	(202,959	)

In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized, and when necessary valuation allowances are provided. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. We assess the realizability of our deferred tax assets quarterly and consider carryback availability, the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment. In 2020, we recorded an additional $1.9 million of valuation allowances against our net deferred tax assets, primarily relating to certain Canadian subsidiaries.

For income tax purposes, we have approximately $1.4 billion of gross federal net operating losses, approximately $49.4 million of gross Canadian net operating losses and approximately $931 million of post-apportionment state net operating losses as of December 31, 2020, before valuation allowances. The majority of federal net operating losses will expire in varying amounts, if unused, between 2034 and 2037. Federal net operating losses generated in 2018, 2019 and 2020 can be carried forward indefinitely. Canadian net operating losses will expire in varying amounts, if unused, between 2036 and 2040. State net operating losses will expire in varying amounts, if unused, between 2023 and 2040.

As of December 31, 2020, we had no unrecognized tax benefits. We have established a policy to account for interest and penalties related to uncertain income tax positions as operating expenses. As of December 31, 2020, the tax years ended December 31, 2014 through December 31, 2019 are open for examination by U.S. taxing authorities. As of December 31, 2020, the tax years ended December 31, 2013 through December 31, 2019 are open for examination by Canadian taxing authorities.

We continue to monitor income tax developments in the United States and other countries where we have legal entities. During 2020, the United States enacted various legislation related to COVID-19 relief, which includes multiple tax provisions. We have considered these tax provisions and do not currently expect any material impact to our financial statements. We will incorporate into our future financial statements the impacts, if any, of future regulations and additional authoritative guidance when finalized.

We continue to elect permanent reinvestment of unremitted earnings in Canada effective January 1, 2010, and we intend to do so for the foreseeable future. If we were to repatriate earnings, in the form of dividends or otherwise, we may be subject to certain income and/or withholding taxes (subject to an adjustment for foreign tax credits).