*118OPINION OF THE COURT
ALITO, Circuit Judge:The United States appeals under 18 U.S.C. § 3742(b)(3) from a final sentence imposing a shorter term of imprisonment than the minimum set out in the applicable range of the Sentencing Guidelines. Because the factors upon which the district court relied in departing from the guideline range were adequately taken into consideration by the Sentencing Commission in formulating the relevant guidelines, we will vacate the sentence and remand for resen-tencing.
I.
The defendant was indicted in January 1990 in the Middle District of Pennsylvania for six counts of distribution of cocaine and possession of cocaine with intent to distribute, in violation of 21 U.S.C. § 841(a)(1). The defendant pled guilty to one count as part of a plea agreement calling for dismissal of the remaining counts.
The defendant’s presentence report concluded that he qualified for sentencing under the career offender provision of the Guidelines, Section 4B1.1. This section provides in pertinent part as follows:
A defendant is a career offender if (1) the defendant was at least eighteen years old at the time of the instant offense, (2) the instant offense of conviction is a felony that is either a crime of violence or a controlled substance offense, and (3) the defendant has at least two prior felony convictions of either a crime of violence or a controlled substance offense.
The term “prior felony conviction” is defined as a prior adult conviction for an offense punishable by death or imprisonment for a term exceeding one year. Section 4B1.2, Application Note 3. The term “crime of violence” is defined as any federal or state offense that is punishable by more than one year’s imprisonment and that either contains “as an element the use, attempted use, or threatened use of physical force against the person of another” or is among the offenses specifically listed, including “burglary of a dwelling.” Section 4B1.2.
The defendant’s presentence report revealed that he was 32 years old at the time of offense for which he was to be sentenced and that he had several prior adult felony convictions for crimes of violence or controlled substance offenses. First, he was convicted in the Dauphin County (Pennsylvania) Court of Common Pleas for burglarizing an apartment in Middletown, Pennsylvania; he committed this offense on June 5, 1975, at the age of 18 years, 8 months. He was sentenced to imprisonment for 11 to 23 months but was paroled immediately to authorities in Virginia to face pending charges. Second, he was convicted in the Portsmouth (Virginia) Circuit Court for the armed robbery of a pharmacy and was sentenced to ten years’ confinement; he committed this offense on September 5, 1974, one day after his eighteenth birthday. Third, the defendant was convicted in 1985 in the Lackawanna County (Pennsylvania) Court of Common Pleas for delivery of a controlled substance and was sentenced to from two to four years' imprisonment; this offense occurred in April 1985, when the defendant was 28 years old. Finally, also in 1985, the defendant was convicted in the Lackawanna County Court of Common Pleas for delivery of a controlled substance and was sentenced to from two to four years’ confinement to run concurrently with the previously mentioned drug sentence. The defendant committed this offense in September 1984, at age 28. Apparently because the last two offenses were consolidated for sentencing, the presentence report treated them as a single prior conviction.1 Thus, for purposes of the career offender guideline, the presentence report disclosed three prior qualifying convictions, although the guideline required only two.
*119Based on these facts, the presentence report concluded that the defendant fell within the career offender provision of the Guidelines, Section 4B1.1. Under this provision, every career offender is given a criminal history category of VI. In addition, a career offender is given an enhanced offense level that is calculated based on the maximum statutory penalty for the offense on which he is being sentenced. In the defendant’s case, the maximum statutory penalty was imprisonment for not more than 20 years (21 U.S.C. § 841(b)(1)(C)). Accordingly, the defendant was given an offense level of 32 (Section 4B1.1(C)). With a two-level reduction for acceptance of responsibility (Sections 3E1.-1, 4B1.1), the presentence report calculated the defendant’s final offense level as 30. Based on this offense level and a criminal history category of VI, the presentence report reached a guideline imprisonment range of 168 to 210 months.
During the sentencing proceeding, the defendant’s attorney requested a downward departure based on a variety of grounds. Defense counsel argued that the defendant’s first two adult offenses “occurred when [he] was kind of a mixed up kid.” Defense counsel also claimed that as soon as the defendant was arrested for the burglary in Dauphin County, Pennsylvania, he confessed to the prior robbery in Virginia, and defense counsel asserted that the Virginia robbery would not have been solved otherwise. In addition, defense counsel asserted that his client was a good father who regularly visited his child and paid child support.
The district court agreed with the accuracy of the calculation in the presentence report but granted a substantial downward departure. The court wrote:
Defense Counsel cited the defendant’s youthfulness and immaturity at the time he committed prior offenses in 1974 and 1975 along with the short time span between the commission of the offenses and the defendant’s cooperation with authorities. Defense Counsel also referred to the needs of the defendant’s dependent child and his past efforts to support the child. Having considered the corn-ments of Defense Counsel and the totality of the defendant’s background the court concludes that a strict application of the guidelines would be irrational.
The court therefore reduced the defendant’s offense level by eight levels to level 22 and imposed a sentence of 84 months imprisonment, which represented the minimum sentence within the range for offense level 22 and criminal history Category VI (84 to 105 months).
II.
The Sentencing Reform Act requires a sentencing court to impose a sentence within the range prescribed by the Guidelines “unless the court finds that there exists an aggravating or mitigating circumstance of a kind, or to a degree, not adequately taken into consideration by the Sentencing Commission in formulating the guideline that should result in a sentence different from that described.” 18 U.S.C. § 3553(b). “This provision is mandatory.” United States v. Uca, 867 F.2d 783, 786 (3d Cir.1989). When we are required to determine whether a departure was based on a circumstance that was adequately considered by the Sentencing Commission, our scope of review is plenary. When we are required to determine whether a departure was based on incorrect factual findings, our standard of review is whether the findings were clearly erroneous. See, e.g., United States v. Riviere, 924 F.2d 1289, 1303 (3d Cir.1991); United States v. Pharr, 916 F.2d 129, 131 (3d Cir.1990); United States v. Medeiros, 884 F.2d 75, 78 (3d Cir.1989).
In the present case, the district court relied upon the following factors as grounds for departure: “the defendant’s youthfulness and immaturity” at the time of his first two adult offenses, “the short time span between the commission of [those] offenses and the defendant’s cooperation with authorities,” and the defendant’s responsibilities with respect to his child. All of these factors, however, were “adequately taken into consideration by the *120Sentencing Commission in formulating” the career offender guideline.
A. Age and Maturity. The Sentencing Reform Act, 28 U.S.C. § 994, directed the Sentencing Commission to consider whether “age” should be considered in sentencing. The Commission subsequently issued a policy statement, Section 5H1.1, that unambiguously provides that “[a]ge is not ordinarily relevant in determining whether a sentence should be outside the guidelines.”
Although this policy statement does not completely prohibit departures based upon age, it proscribes such departures except in extraordinary circumstances. In the present case, neither the district court nor defense counsel identified any extraordinary factor relating to the defendant’s age at the time of the first two offenses. Certainly the bare fact that the defendant was 18 years old when he committed those crimes is not extraordinary. On the contrary, the commission of crimes of violence and drug offenses by 18-year olds is distressingly common.
Nor do we believe that the defendant is entitled to a departure simply because the Pennsylvania and Virginia courts might not have treated him as an adult offender had he committed those crimes a short time earlier, when he was still 17.2 Cases involving youthful offenders that just qualify for adult treatment — and cases that just miss qualifying — are common. Simply because a case falls close to the line does not make it extraordinary. If we recognized a zone of extraordinary cases extending for some period of time after the statutory cut-off, we would undoubtedly be confronted with cases falling just beyond this zone and would then be required to decide whether these cases were also extraordinary. We decline to embark on this course.
For similar reasons, the defendant’s asserted immaturity at the time of his first two offenses does not justify departure from the guideline range. If the sentencing judge did not simply use the term immaturity as a synonym for age, the court may have been relying upon defense counsel’s claim that the defendant “was kind of a mixed up kid” at the time of these crimes. The quality of being “kind of ... mixed up,” however, does not justify departure. See Section 5H1.3 (“Mental and emotional conditions are not ordinarily relevant in determining whether a sentence should be outside the guidelines, except as provided in the general provisions in Chapter Five.”)
B. Time Between Offenses and Cooperation. The length of time between the armed robbery of a pharmacy in Portsmouth, Virginia, on September 5, 1974, and the burglary of an apartment in Middle-town, Pennsylvania, nearly nine months later, on June 24, 1975, does not justify departure. The Sentencing Guidelines contain detailed rules regarding merger of offenses for purposes of calculating criminal history category and applying the career offender provision. See Section 4A1.2(a)(2) and Application Note 3; Section 4B1.2, Application Note 4. Under Section 4A1.2, Application Note 3, cases are generally merged if:
They (1) occurred on a single occasion, (2) were part of a single common scheme or plan, or (3) were consolidated for trial or sentencing.
By adopting this approach, the Commission implicitly rejected any rule that would merge the defendant’s first two adult offenses simply because they were committed within the space of nine months. Moreover, even if those offenses were merged, the defendant would not escape the career offender guideline because he would still have two prior qualifying convictions.
Similarly, defense counsel’s assertion that his client cooperated with the Pennsylvania and Virginia authorities did not justify departure. Under 18 U.S.C. § 3553(e) and Section 5K1.1 of the Guidelines, a sentencing court cannot depart *121downward based upon a defendant’s cooperation unless the government makes a motion to permit such a departure, see, United States v. Bruno, 897 F.2d 691 (3d Cir. 1990). No such motion was made by the government in this matter.3
In the present case, there are no exceptional circumstances relating to any past cooperation by the defendant. It must be assumed that the sentences he received for his prior offenses reflected consideration of any cooperation he provided to the degree that the Pennsylvania and Virginia courts felt was appropriate. Departure is not justified simply because this method of taking cooperation into account does not remove his prior offenses from the scope of the career offender guidelines.
C. Family Responsibilities. The Sentencing Reform Act, 28 U.S.C. § 994(e), directs the Commission to “assure that the guidelines and policy statements ... reflect the general inappropriateness of considering the ... family ties and responsibilities ... of the defendant.” The Commission, accordingly, has stated that “[fjamily ties and responsibilities ... are not ordinarily relevant in determining whether a sentence should be outside the guidelines.” Section 5H1.6 (policy statement).
In the present case, the defendant’s pre-sentence report revealed that he has a young son who resides with the defendant’s former wife, that the defendant has paid regular child support, and that the defendant frequently spoke with the child by telephone. Defense counsel added at the sentencing hearing that his client is a good father and regularly visits with his son. These facts do not show such extraordinary family ties and responsibilities as to justify a departure despite Section 5H1.6.
III.
Because the circumstances upon which the district court relied were adequately taken into account by the Sentencing Commission, the Sentencing Reform Act, 18 U.S.C. § 3553(b), prohibits departure on those grounds.4 Therefore, we will vacate the sentence and remand for resentencing.
. This treatment was prescribed by Section 4A1.2, which is "applicable to the counting of convictions” under Section 4B1.1. Section 4B1.-2, Application Note 4. Under Section 4A1.-2(a)(2), "related” sentences are treated as one sentence, and cases that are consolidated for sentencing are regarded as “related." Section 4A1.2, Application Note 3.
. In both Pennsylvania and Virginia, offenders under 18 years of age were generally treated as juveniles but those over 14 in Pennsylvania and those over 15 in Virginia could be tried as adults in certain circumstances. Juvenile Act, Dec. 6, 1972, P.L. 1464, No. 333, §§ 2, 7, 28, 1972 Pa. Laws 1464; 1973 Va. Acts, ch. 440, § 1; 1974 Va. Acts, ch. 44, § 1.
. Moreover, the career offender guideline already incorporates a considered decision by the Commission regarding the way in which cooperation for prior offenses generally should be taken into account. Under the career offender guideline, only those convictions resulting in prison sentences exceeding one year are counted. Sections 4B1.1, 4B1.2 and Application Note 3. If a defendant provided cooperation before sentencing for a prior offense, the sentence imposed for that offense presumably reflects consideration of that cooperation to whatever degree the sentencing court felt was appropriate. If the prior conviction resulted in a sentence of less than one year in light of cooperation, that prior conviction is not counted under the career offender guideline. Conversely, if the prior conviction resulted in a sentence exceeding one year despite cooperation, that prior conviction is counted. This scheme takes past cooperation into account, but it does not call upon a federal court applying the career offender guideline to perform the daunting task of making a new assessment of cooperation furnished in relation to past offenses. Because this scheme already takes past cooperation into account, departure based on past cooperation is generally not permissible. But see Section 4A1.3.
. In light of the dissent’s discussion of broader sentencing issues, we emphasize that we have decided only that the sentencing court erred in granting a downward departure based on the factors it identified: age and immaturity, the short time between offenses, cooperation, and family responsibilities.